I have felt this as well. For me it was because I went from being a professional where I received praise all the time in the form of a paycheck, raises, promotions, positive client and supervisor feedback, etc. to being a stay-at-home mommy, where no one thanks you for all the hard work or tells you that you are doing a good job! And, you have to be self-motivated and set your own priorities. These were hard for me to do since I was used to fulfilling others' requests professionally.
What I've learned in the past 2.5 years since I've been a mommy and housewife (geez, how did this happen?! :) is that everyone does things differently, so there is no "right" way to do things, so no one can give you approval. Know what I mean? Also, are your kids generally happy and do you have a good relationship with them? If so, then you are doing a wonderful job!
And are YOU happy? The first year I went to ridiculous lengths to do the "right" think for my baby girl. I was miserable, and looking back I think I spent much too much energy trying to be perfect, and not enough energy in being happy. I think if I'd been more flexible and taken some short cuts the entire family would have been happier.
I'm living in Italy right now, and there is a saying that goes something like this: "fare il meglio non fa bene". It means that doing the "best" thing isn't good for you. And I think that's true. When I see uptight mommies (like me!) and compare them to really relaxed ones, I think the relaxed ones are having more fun, and so are the kids. And the kids aren't missing anything.
Anyway, that's just my opinion! Like another mommy said, think about what's important to YOU and let that guide you. No mommy or wife can be prefect or do everything. But when we do things with love it is absolutely good enough!
Hugs to you,