She doesn't look overly fat OR pregnant in the pic on green grass, so why did you post that one??
Others on snow, she doesn't loo obese but hard to tell with those pics. However, while obesity is not good for anyone, a little overweight before dropping a goal & lactating is generally fine. Not an expert but she doesn't look obviously ready to drop.
These posts pop up regularly, but I don't think anyone can tell if a mare is pregnant from looking at photos. Probably best to have her checked by a vet. She does look rather thin in the picture where she's on grass. Is she a hard keeper or an older mare?
Were you feeding her like a pregnant mare? If this mare is 9 or 10 months along she has anywhere from 4-6 weeks left to foaling and I would say she looks far too thin if she is bred. If she is bred she is way too thin and the health of her foal could be at risk.
If the vet confirmed she was in foal why would you doubt she is still pregnant?