Advice pls

I’m going out of my mind. I finished mat leave with my second child and got offered a job giving me the specific hours I needed to fit round childcare. I explained hours would need to change when my lo started full time in September and of course that was fine. Now there’s been constant battles with my manager for keep putting me on shifts she knows I can’t work, at least every other week. September has come and despite her knowing I needed to swap to the earlier shifts she’s changed me to the later ones. I’m going out of my mind. It’s literally every single week I’m having to speak to her and still I’m not being listened to! I’ve tried being nice about it but I’m just so pissed off that I’m being ignored! Also been treated like absolute shit since they found out I was pregnant, I kind of feel like they’re doing it deliberately to try and push me out. It’s making me not want to go but obviously I won’t get another job now I’m pregnant. I’m just at a loss and don’t know what to do. Speaking to them is pointless because nothing changes and I don’t get listened to but what else can I do?