Unfortunately, on face value, and from what you share, you probably don't have a case against your company. If you truly aren't qualified for the job, there really isn't much you can do.
However, if you have any proof of discrimination being an underlying cause for not being considered for this position, you may have a case...but you'll also have your work cut out for you. And hiring an attorney will be very costly upfront, long before you recoup any money.
If it was public knowledge that you were pregnant at the time of your firing, you may have a case. If your employer/supervisors referenced your pregnancy as being a reason you aren't qualified to do your job or aren't eligible for consideration of any other job within the company, you might have a case. However, the burden will be on you to prove that your layoff was indeed because of your pregnancy.
Considering your supervisor is getting fired too, you will be hard pressed to prove it is because of your condition, and not because they are changing direction with your department or the overall operation of your company. Race, age, and sexual harrassment (overlooked because you're female or mistreated because of your sex) of course would be causes .
You might be better off looking over the terms of your contract (if you have one) with your company. Considering they moved you to a new location for this position, was there any promise of training, a timeline of training, and then a clear-cut layout of expectations? What about regular performance reviews? Do you have records of these performance reviews and do they detail your skills and growth on the job? Is there any other information that would point to a breach of an agreement on the part of your company with you concerning your new job such as a promise of continuing education to make you viable to the company and your job?
If they have failed to follow-through on any policies or contractual agreements you may have a case.
The best way to find out if you have a case or your case is worthy of court action, you should contact an attorney who specializes in employment law. As for conversations with employers and especially co-workers (who are often enlisted to build a case against you if they suspect a lawsuit) about your layoff, etc. should be minimal to non-existant, and if necessary, purposeful if you do think they have violated the law. Any and all documentation on your part can be used against you. So be very careful about all correspondence, e-mail and conversations from here on out. Likewise, you should keep careful records of any and all correspondence as well in a safe place, and offsite, so if after you leave, you have them if you need them (for legal purposes or otherwise).
Lastly, but most important: CAREFULLY EVALUATE WHETHER LEGAL ACTION IS WORTH IT! If you work in a very specialized field or the pond where you work is very small, you may burn a lot of bridges. You may win the battle, but lose the war if you go to court. Just be careful and really carefully weigh whether going to court is worth it. It might be easier to just ride it out, chalk the place up to being a dump, and move on to greener pastures. Think about what you hope to gain by suing. If you do keep your job as part of a settlement, consider how hostile the environment will be thereafter. If you settle without a job, you may have a chunk of money, but your name might be mud in your industry, or you may lack references and important connections for future work. Just be careful. You're young and now you have a family to support.
Regardless if you have a case or not you should do the following:
You won't be eligible for severance unless this was part of your employment agreement from the beginning. You can however, apply for unemployment which will mostly provide about half your monthly income up to 6 months (unless things have changed ...you might want to check. with MN Work Force)
If you have health insurance with your current employer, apply for COBRA coverage (extension of health benefits for period of time past your employment). You will have to pay for this continued insurance coverage, but costs will be significantly less than if you had no coverage at all.
If you have a 401K or any other investments with your company, make arrangements with a financial planner to have them rolled over to avoid any taxable events or loss.
Be prepared to be asked to leave immediately without warning and without notice. Consider your last day, could be any day and at any moment. Especially if you have the sort of job where you have access and knowledge of products or collateral that would be useful to a competitor...or they feel your presence could jeopardize the company legally speaking. Many employers will just ask you to leave, and not give you time to get items out of your office or to say goodbyes.
With that said, if there is any paper work or projects that you need or want to keep for a portfolio, be sure you have copies of what you need now. Be sure you have references from supervisors and employers now, so that you have them when applying for a new job.
Be careful however, not to take anything that can be construed as your company's property (intellectual or otherwise) such as software, documents, etc. They could use this against you, and take legal action.
As for looking for employment while pregnant...very challenging. Depending on the type of work you do, many may be hesitant to hire you if they need someone who can put in long hours. For many the prospect of losing someone for 6 weeks right off the bat may be a deterent.
Other potential employers are leary of people taking advantage of them for insurance coverage, only to never return to work.
It doesn't hurt to apply places. But if there is a company you really want to work at, I think I'd wait to apply until after the baby unless you know for certain they are very mama/baby friendly. Unfortunately, in this economy, there probably is a shortage of that.
In the interim, consider working for a temp agency or on a free-lance basis to give yourself flexibility (maternity leave won't be an issue), maintain contacts in your field, and a stream of income. For many, temp work can turn into full-time work.
Read books on how to price your services so that you will be able get self-employment insurance and are able to afford the cost of running your own business. Who knows, you may like being on your own so much, this might be your second career.