Can I just ask why did you not have her scanned when she returned from the stud? We would have always scanned mares at 21 days to 1) check they were indeed in foal and 2) make sure there weren't two in there!
She doesn't look to have a large belly, in fact if my eyes aren't playing tricks on me she looks heavier at the 2 months photo than the most recent. Saying that, she is a maiden mare and I would get a vet out to check her right away.
Stop for a minute, open your mind, learn. You may not agree with what I say, I may not agree with what you say but we will both learn something new.