The first 3 months went relatively smooth...biggest change for me was getting used to getting up all hours of the night to feed Mason (if one can actually get used to that :). Mason did a lot of growing during this time. He went from a newborn size in clothes to a 3/6 month by the time he was 3 months old. I guess being a hybrid baby (my turn for combining breastfeeding and formula feeding) worked well ;).
My mom said I shouldn't worry about not only strictly breastfeeding him because some women conveniently forget that breast is ONLY best when the mom's diet is good and a new mom's diet is rarely good (unless she has a staff to take care of her, lol). So I got over that quickly. It also helped that when Mason was offered his first bottle of formula, he took it without skipping a beat....almost like "Oh, this is where dinner is coming from tonight".
At first he seemed to have some minor issues with gas, but that changed when we changed bottles and formula. He was using the Nuk bottles at first because they came highly recommended for breastfeeding moms but he seemed gassy, so we switched to the Playtex nursers and the gas improved. He was still a little gassy so we tried another formula (Similac Sensitive). That switch was awful.... majorly fussy baby! So after that horrible switch we went back to the old formula, still a little gassy but better than the new formula. After a while (and a lot of research) we chose a formula for gassy babies (Enfamil Gentlease). Finally! The magic combination (Playtex nursers and Enfamil Gentlease)!!
By the end of his first three months he was smiling and laughing, cooing and able to recognize his name.