I wouldn't say that the pony looks in foal. It just looks to be one of those breeds that sturdy, hardy and have a barrell belly. I had a shetland that was exactly the same. Admittedly, could do with losing a few kilo's, but I'm sure with work, he/she will get there.
Futolympiceventer327 is right about the stirrups, although on pictures 14 and 17, she looks to have a nice deep seat, back straight with good leg position, and this has made weight go down into her heels. Looks much better.
Only other thing I noticed, is in some pictures she tends to give too much with her reins, on the approach. Some pics she gives less than others.
She definitely looks to be enjoying herself.
Be good to see her riding on the flat if you have any? :)