Noobie, I'm not sure that I have answers for you, but I'm sending you big hugs. My first thought on this is that while you are pt, it might not be so bad. As you say, you aren't there when all the meetings are anyway, and I'm sure that it's really good being able to bf at lunchtime and leave early enough to have time with your bub, instead of being overworked and doing more hours than you would like. I can fully understand how frustrating the situation is anyway, but maybe you can use this time to ease into the workforce again, and then address it when your real supervisor returns.

Now believe me, I know this is easier said than done. Truthfully I'd be feeling stressed and upset too if it was me. But I do know that my attitude to work is different post-kids than it used to be, and I do prefer to be "comfortably busy" and be able to be home to the boys at a decent hour, than stressed and working back. If you can just ride it out for a little bit, until the supervisor returns, you might find there are some benefits. Just think of how nice it is having time with your bub.

Best of luck with it. I hope you feel happier about things soon.