Check her nipples. I'm not exactly sure whether it happens to all piggies when they are pregnant but all of my piggies nipples got very large when they were preggers. Also, if she's older than one year old, you need to take her to a vet and keep a close eye on her. If she hasn't previously been pregnant before the one year mark there are major concerns involved...the life or death type. I've been through four pregnancies with my piggies (don't ask, it's all in my profile) and I was lucky everyone survived. She looks like she may be pregnant to me, but not too far along. If you pick her up under her arms does it still buldge out around the tummy like that? (You should always support their bums but just to see what happens this once can't hurt her) If you've still got a big buldge on each side when lifting her from under the arms she's most likely pregnant. Did you get her from a pet store or something? I only ask because rescues usually know if their sows are preggers or not and don't house entact males with females. Good Luck either way.
Oh, also, is she drinking more water than usual? Her bottle look emptier when you go to change her water? Because my piggies drank like twice as much water as usual when they were pregnant. I would fill a large one when I left for work in the morning and by the time I got home it was close to being empty!
