Would this offend you- MIL-oh, no, she didn't?

I know this sounds petty but, it's just the tip of the ice berg. When I got pregnant with my son, my MIL's first Grandson, I gained a good deal of weight. I lost most of it but am still a little chubbier than I was before I got preggo. My son is now 2. She is always saying rude comments to me about it. Well, today, she called to ask what size ring I wear. I explained to her that I wear a 7 on my left hand ring finger but that my right hand is just a wee bit bigger so probably a 71/2 or 8. She exclaimed "Nikki (her youngest, very thin daughter) wears an 8, I think I'll get you a 9." I seriously got sad over it. I know I should be grateful for whatever gift she's getting me and try not to be caddy, but would you be offended too? Is there anything I can say to her that will get her to realize how hurtful she is being?