BFP, now what???

Pamela
I just got my BFP! I am 3 weeks and 4 days!! I guess I am just wondering.. now what? Do I go to an OBGYN to confirm? Or to my general practitioner?
What am I allowed to eat
How much water do I drink
Is coffee allowed
I just have so many questions, and I don't know where to start, this is my first time!