I have one regret and another that I wouldn't call a regret, but I know I would do differently if I ever have a second child.
Regret: We hadn't planned my daughter and my husband was still in grad school finishing up his PhD when she came alone. This meant that I had to go back to work (I had always intended to be a SAHM) and left my daughter with my mother. Now, that's not my regret as my mother was excellent with her. However, I was a teacher and my principal wasn't the best with new and nursing mothers. She was certain that there was no way I could do both my job and be a new mother, so she was in my classroom multiple times a day asking me if I was sure I was getting my lesson plans done (I always got them turned in on time), randomly quizzing my kids (who, btw, always passed her stupid little quizzes), and just micromanaging me. She also decided that she wanted me to try co-teaching with a general ed teacher, but coudln't make up her mind which class period I would be in her classroom. My schedule was constantly changing which made pumping on schedule next to impossible. My final schedule ended up with me having my conference period and my lunch period back to back. I tried pumping on my conference period, but I shared a classroom so I needed a private place to pump. She took issue with this and told me that I needed to do that on my own time and not during working hours. So then I was only able to pump during my lunch break. By this point, the stress and the inconsistent pumping led to low milk production. My doctor suggested that my daughter come up to the school during my lunch break to nurse as babies can always get more than a breast pump can. My principal took serious issue with this. Now, understand that multiple teachers had their husbands, parents, friends, or children join them for lunch on multiple occasions as this is supposed to be our own time. My principal said that my situation was different because none of them were requesting a private place - they all just sat in the lounge. I wanted a room to nurse my daughter so I didn't have to take my breast out in front of teachers, children, and such. The stress and inconsistent pumping/nursing really did a number on my production. However, since I was nursing exclusively at this point and not pumping, I didn't realize how much until we noticed my daughter was losing weight. At her seventh month check up, she was diagnosed with failure to thrive due to her weight loss. We had to supplement with formula, which I was fine with except for the realization that she was on formula because I wasn't standing up for myself and my child. I met with HR in early November and was able to leave mid-semester and still get paid for the year. I always wished I had spoken up earlier instead of just trying to keep the peace.
Differently: For the first few weeks of my daughter's life, I was absolutely terrified of SIDS. Like most infants, she didn't want to sleep in her crib. We had her sleep in her carrier/car seat and that worked well for her. Unfortunately, I was a nutty first time mother who was convinced that my little baby, who couldn't even hold her own head up, would be able to roll over and smother in her carrier. So, at night, I would sit up watching her sleep to make sure that her blanket didn't creep up over her face and that she didn't roll over and smother. I was exhausted. I would stay up until someone else in the house (we stayed at my parents the first few weeks) was up. Then, I would ask them to watch her and I would get about an hour to an hour and a half of sleep before I had to get up to feed her. I was absolutely exhausted.