Not going back?

I am currently a teachers aid contracted to a school through a recruitment agency in NJ. Our official school year ended in June, however I did work part time in July doing a summer school program. We had off in August and now are set to start back to work next week, the first week of Sept.

My contract is ongoing there is no set end date even during the summer hours, I just don’t get paid in the summer but I still have my health insurance coverage and start getting paid again in Sept. My question is if I quit next week during the first week of school, is it possible for my company to back charge me my insurance premiums or anything like that for August and possibly July since my hours were part time.

One friend told me that is a possibility if I don’t work at least one day in September, however another friend told me she didn’t think they could do that.

So is that a possibility if I quit on the first day of school or do I need to work for a couple days before I quit so I don’t get screwed paying for July and August?

(I love my job and I know it’s shitty to quit last min but I am very pregnant and do not qualify for maternity leave with my company since I have not been there for a year. I’m not worried about losing my insurance I am now covered under my husband’s plan, I just don’t want another financial cost before baby if it can be avoided)

Thanks!