Former competitive swimmer here too. I swam last pregnancy pretty regularly--haven't swum much thus far with this one because I feel so crappy and lap times aren't coordinating with times that I have someone to watch my dd.
Anyway, I think your workout sounds fine. Also, I did backstroke throughout my pregnancy without problems, so not sure if you're avoiding it because you're not supposed to lie on your back on the ground. I found it hard to "steer" because I would get distracted watching my belly pop up above the water :) but it felt completely comfortable the entire pregnancy. I started avoiding breast as I got bigger because I felt it put too much pressure on my low back and I also had some pubic symphasis stuff going on, so the kick didn't feel great. I feel like the kickboard also puts stress on the low back, so I did mostly streamline kick, especially dolphin on my side. (FWIW, I have some significant low back issues and am particularly aware of what stresses the area for me--you know, aside from having a huge stomach and sway back;)
Being in the pool is a great opportunity to get some good stretching in using the wall. And, if you have a few minutes at the end of your workout, I suggest grabbing a noodle, tucking it under your arms and floating while you do some kegels. By the end, just floating will feel so good that this might become the extent of your workout! I found it annoying to swim swim the last month of my pregnancy because I had no core anymore and my hip rotation just felt silly.
Good luck mama!