Hi T. - I haven't experienced all the issues you are going through, but I have plenty of experience feeling like an overwhelmed and worried mom, and dealing with working outside the home and being away from your baby all day! I have two girls, ages 3 and 17 months, and they both were in day care by the time they were 3.5 months old. Three years later and it is STILL tough sometimes to send them off and miss them all day, wonder how they are, etc. I also enjoy my job and I know myself well enough to know for a fact that I do not want to be home with my kids 7 days/week, but I yearn for the ability to do part-time... not happening right now anyway! So I hear you about the financial aspect of working motherhood. All I can say as far as that goes is to remember that you are not doing your baby irreparable damamge, as some would have you believe, by sending her to day care. My girls are extremely well-adjusted, spend plenty of bonding time with me and my husband, and are very happy and content little beings! We make the most of the nighttime hours, vacations, and weekends, and while it is tough and they days can be long, it has worked out for us thus far. It is tough to deal with the way the world is today and the way we are wired as moms - we have that natural desire to be with our kids but we also have to work for a living or we couldn't afford the kids! That is a major contradiction in my opinion but it's out of our control. The only thing you can do is try to deal with it in a way that works for you - maybe there is a co-worker you can vent to who is in the same position? That helps me at work.
As far as the baby gaining weight, I did not experience that directly with my girls, but it sounds like you are doing everything you can and should be to help her. I think mixing the formula with breastmilk is a good idea so she gets the benefits of both. I have also read that the supplement called fenugreek is great for increasing your milk supply so you can keep pumping. The "good fats" the previous poster mentioned are healthy and a good idea for us all to eat no matter what (olive oil, nuts, flax, avocados, etc.). You should be proud of yourself for continuing to breastfeed despite an infection and D & C after everything you went through - wow, that is a lot to deal with! You are doing the best you can and you should give yourself a pat on the back for that! You are obviously on the right track. Let us know how it goes!! Hang in there!