I'm full time, pregnant, and they took away my PTO

I stopped accumulating PTO and I cannot use any that I did have accumulated. No one informed me of this I just happened to notice on my work app and paystubs. I'm rightfully pissed seeing as their excuse is that I fell below the 130 hour mark for a couple months so now I'm only accumulating sick pay which is about 4 hours a month when PTO was 10 hours a month. I had 41 hours of PTO saved and it somehow says I have 34 hrs total even though I haven't taken any and now I don't even have the option to take any.

So my hours dipped below the threshold because it was the slow season and literally there was no work. They kept calling me off and when I was there I got done early and there wasn't anything left to do so I went home. I'm getting punished for something out of my control. Not only was I not making enough on my paychecks those months, but now I'm not getting PTO anymore and I need that for my maternity leave in June. They are all aware I'm pregnant. I've worked for this company for 4 years and never had this issue before. I'm also an excellent worker that goes above and beyond often and is very reliable. I feel wronged.

I'm fuming because my boss just shrugs about it and I can't talk to the finance person until next week probably and I know they are also not going to care.