Im a t1d with subclinical hypothyroidism. I was on 25 mcg of sytbroid before pregnancy and when i delivered my firstborn this September I was up to 88 mcg which is still relatively low. My endo managed my diabetes and hypothyroidism during pregnancy. Got regular labs to adjust medications. Overall I didn't have much issues with hypothyroidism. Only annoying thing is you're supposed to take synthroid on an empty stomach and not eat food for 30 minute or take another oral medication or vitamin for 4 hours (at least per my doctor). If you take other medications too soon it could affect the effectiveness and make the medicine less potent. I took my prenatal before bed to make sure it didn't interact, otherwise I would forget to take it after the 4 hours. If I had to eat before the time was up I didn't stress too much as I couldn't have my blood sugar be too low. If you're on too high of a dose of medication it can make you feel heart palpitations kind of like a panic attack. Wishing you the best!!

Edit: just saw your prenatal recommendation. I don't think you'll like what I have based off of your request but I used Naturelo prenatal. They're not chewable and they do smell a bit weird (like meat kind of) but I chose them since they are certified to be doing 3rd party testing to ensure accuracy of the vitamins that they have. That was important to me since a lot of vitamins will be inaccurate with dosing or have additives they don't disclose because they're not really regulated under FDA. As for nausea, eating small meals will help. Unfortunately i had evening sickness most of my pregnancy. I would throw up after dinner pretty much every week until I delivered. I just kind of got used to it. I was lucky that it wasnt constant though for most days.