I could have written this myself, minus the 7-8 hour stretch of sleeping, lucky you :) My son is also almost 10 weeks, but this has been going on since about 5 weeks. He does have silent reflux and is on Zantac. It did not change his eating habits.
My pediatrician also recommended rice cereal to stretch feedings longer, but he doesn't do well on it. He groans and moans and it just seems like his tummy is upset from the rice. I even reduced the amount I gave him from 5oz to 4oz when the bottle has cereal in it. Overall I stopped after 2 feedings.
Additionally my pediatrician did not call him overweight. He is only in the 55th percentile. He was 1 month premature, but is being measure against full term babies.
I've read many places that the average baby should eat 2.5oz of formula per 1lb of body weight. My son weighs 12lbs 1 oz. So that's about 30 oz per day. Let alone he keeps gaining weight so I feed him 30-32oz per day. I don't know if there is a limit on the 2.5oz per 1lb of body weight, but I would think if he was 15lbs he'd need more than when he was 12lbs. Until we start on solids I'm just going to stick with that calculation. I weight myself and then weight myself holding him to see if he gained the next pound.
Unfortunately he can't go longer than 4 or 5 hours at night so he still has 7 bottles a day. I even tried to give just one big bottle before bed, but he will still get up and then overeat so I just divide the total amount per day by the amount of bottles I give him. I may give rice cereal a try in a few more weeks, but overall as long as he is healthy, gaining well (not too much or too little), peeing a lot, and pooping I feel I'm doing alright.
I know people say if they are hungry feed them, others say don't over feed them, add rice, don't add rice. The internet is filled with a bunch of opinions. Each opinion usually has so called "facts" to back what they are saying. You have to do what you feel is right for your baby.