Oh how I understand what you're going through... So 5 years ago during my pregnancy I broke out SEVERELY! Going from crystal clear to cystic pizza face and no one could help! So let me give you some advice. Since them, I've gained 100% more knowledge and am better prepared for my next pregnancy. Definitely never use Retin-a. Since there have been not too many studies on its effects on the fetus, I'd stay away, at least for the first trimester. You don't want to use benzoyl peroxide. I don't use it period because it did during pregnancy and still does leave me brown...???!?!?!! Weird... Keep away from antibiotics. I was even put on erythromycin because it was horrific and it helped nothing! So if it's gonna stay the same u might as well exclude it on your list. Make things easier, let me tell you what you can use and what's perfectly safe durin pregnancy:
Glycolic acid 10% as a daily treatment both night and day/ keeps skin smooth and exfoliates
Glycolic acid peels no more than 30% to STAY safe/ exfoliates, kills bacteria, lightens spots
Mandelic acid 25% peel, used once a week to battle the acne from forming
Salicylic acid peel no more than 20% used on a monthly basis and only left on the skin for 1 minute (believe me a minute is all you need and it won't reach the blood stream)/ kills bacteria and oil that causes acne
Lactic acid 40% used bi weekly to exfoliate skin and lighten spots, helps acne
Now I'm not saying use all at once or together, however I will use all of these as directed when I'm pregnant. As a face wash I use baking soda it a scrub I buy from my esthetician. If you want to try any of these id start with glycolic acid. And so you don't waste money, go to sephora and ask them for a sample of Peter Thomas roth 10% glycolic acid. Looks like a clear gel. I'd also begin washing the face with baking soda every other day and maybe sea salt and warm water. These will clean and helps lightly exfoliate your skin without being harsh and making things worse. If the glycolic works for you order from make up artists choice dot com (all one word when typed in search box). I order from them because it's way cheaper to do my own than pay an esthi to do it at $60 a pop. You pay half of that or less and get months worth. Hmmmmmm.... Tryin to see what else I can suggest...
I think that's pretty much it for now. This was real long only because I feel your pain and wanted to explain a bit more. Inbox me if you have any questions. Breathe deep, be happy! You're pregnant and beautiful no matter what!
I knew I forgot!!!! Diet is EXTREEEEEEMELY important! Get a lot of veggies, try juicing i you can and try to cut out dairy and red meat if you can. Soy also sucks because it's like estrogen. In my case it went to hell because I didn't know better. At least start with the dairy. That's what made my skin stop breaking out in cysts, eliminating dairy

hard but worth it and been dairy free for 3 years! Again, inbox me if u have any questions. Good luck!