Weight loss... Too much??

I thought the weight loss was suppose to slow down once you got pregnant.. Yup I said pregnant.. We found out on Easter that we are expecting a Christmas baby!! Finally after 3 years of trying the one month we really stopped trying it happened.. I don’t know if was the stress stopping us from conceiving or if it was 70 pounds I had to lose, either way once I lost the weight and stopped stressing… it worked.. We are now about 6 weeks out and are very excited but very nervous. I have lost 12 pounds since finding out.. And I am not sure how much weight I am suppose to lose.. I hope I am not losing to much.. I have another doc appointment in the AM and an U/S on Wednesday.. I hope everything is going to work out ok.. Wish me luck!