Possibly losing my job bc I'm pregnant

I'm a groomer and have been grooming for 10 years. I've been with company for 5 years, since they opened their doors. When I started I brought my clients, but they had around two dogs a week. Now, I'm booked constantly 2 weeks out, 4 around the holidays. My husband works there on Saturdays, more as a favor to me. I told my boss as soon as I found I was pregnant bc I had to stop grooming cats and crazy big dogs. They were fine with it, my husband took them over. Well 2 weeks at 21 weeks I went into preterm labor. My doctor put me on bedrest for the remainder of my pregnancy. Their goal for me is 28 weeks. I'm now 23 weeks. They don't think I'll go further. Well I was told everything would be fine, I'd have my job when I got back, I'm a great employee etc. They said they were going to try to get a temporary groomer just to take over while I was out. Yesterday, I received a letter in the mail stating that, they are not legally obligated to keep my job and are hiring a full time groomer. It also said they would try to still have a position open blah blah blah. Apparently, even though this chain has 10 places, bc there is not 50 employees in a 75 mike radius, they don't have to go by FMLA. I was so upset, crying my eyes out. I put 110% into my work. My clients are more my friends, and I truly love the dogs. I had no clue I would be treated this way. Is this even legal? For goodness sakes, my husband is still there trying to help while I'm gone! I was out a month last year, workers comp, I had hurt my shoulder and no one came in. They all waited. The poor temporary groomer was back down to 2 a week. So I'm sorry of this sounds bad but I hope it happens again. I've already had people call me to find out what's going on. Sorry I know its long but had to vent

Update: I know it has been a while but a lot has happened. I'm still pregnant :) my job recently hired another groomer and are terminating me june 11. My baby is due July 11. Today my boss and I talked and she said she wants me to reapply immediately when I can come back. Its a real 180. It really took me by surprise. Later today we found out we got aprroved to open a shop of our own! I am so excited and so scared. We have been praying for this for a long time. I love my clients and appreciate getting calls almost everyday. Thank you to everyone for suggesting opening something on our own. We should open the end of august. :) Don't know how to tell my job. Kinda nervous about it. Apparantly the new groomer has little to no grooms booked yet my husband is booked until the end of july with a waiting list a mile long. Please continue to pray for us. Its a scary thing to open a shop.