Breastfeeding and trying for baby #2

Hello! I have an 8 month old little boy and I just got my first period postpartum yay! I want a relatively small age gap between my little boy and new baby. I KNOW 2 UNDER 2! I know it will be hard but I'm very excited and optimistic about it :) Anyway I want to continue BF my son for now at least until he is 12 months, I heard that if you get preg whilst BF the supply can dip or dissapear altogether :( this is something Im not prepared for as my son uses BF for comfort a lot and I don't want to take that away from him just yet, is there a way to make sure my supply doesnt dry out if I do become pregnant within the next couple of months, I would consider tandem BF but not sure if my son will be too old for it or if it would be even possible with 2 children help! 😆