Hey J.! Gorgeous name, that's my daughters name!
Milk may suprise you... It did us... We were told to stay on formula longer then we'd expected... BUT if your son hasn't had any medical issues, or feeding complications, you probably are fine to switch. I would call your doctor, and leave a message on the nurses line (or however yours is set up) and ask. They may be able to look at his chart and determine one way or the other... I would always suggest the doctor because you don't want to have any suprises if you try it on his own. And NO don't take him to the doc just for that! We catch some silly virus every time we're in there so avoid that at all costs!
As for the sippy cup vs bottle. I know it seems odd but you may try a straw instead! Sippy cup is okay from time to time, but if you can get him to go to a regular every day straw you'll save yourself so much heartache! They learn so much, its better for their mouth because it actually helps them develop different muscles etc to help with speach, and they also learn how to drink without tipping the cup (over time but it does work!). I've seen kids of ALL ages still tipping the cup and making messes when they are older... This will avoid that as he gets older. Plus some kids have a really hard time getting off the sippy cup... Sure you have to supervise more of the drinking but in the long run I'm so glad we did that!
Now we don't have to have a sippy cup with us everywhere. We can just stick a straw in whatever we're drinking (bottle of water or cup of juice at the restraunt) and we're set..! That was a tip we got from ECI and its paid off big time!
As for the milk part, don't be suprised if he doesn't want MILK from something else! It took us a long time (in fact we're still working on it) to get her off the night time milk bottle. We're off the bottle now, but she doesn't gulp down a glass of milk like I'd hope! Loves water and juice and everything else but, there is something about milk that is different...
Just be prepared for it! Another thing I've learned was that they actually only need 2-3 servings of milk a day. So you can make that up with calcium rich OJ, cheese, yogart, stuff like that too. But that may be for when he's a little older... Get on the same page with your doctor is going to be your best bet... Find out if you can start milk now, and if so you can give that a good try until his 1 year check up and discuss everything in detail with your doc then!
Good luck! Glad to help!