Holy crap i'm pregnant

Sarah
So i found out i am pregnant last night!(woohoo!) but i feel like i am stuck where do i start? Do i need to start sleeping differently? Can I take benadryl? (alergies) Can i go swimming? Can i have sex? what is the best prenatal? I feel fine is that normal? How much water should i be drinking? My doc wont see me for another 3 or 4 weeks. This is my fourth time being pregnant and i dont wanna lose this one. Help me seasoned mamas!