Trying to make sure that my shelter pig Lilly is not pregnant

Hello everybody! I adopted Lilly from my local humane society/county animal shelter. They said that she came from a surprise/unexpected litter. For that reason, I am trying to be on the lookout for signs of pregnancy, and I want to make sure that she is not pregnant.
I do not think she is, but I need to make sure and keep an eye out on her, of course.

I thought there might be a chance that she could be preggo, because she came from an unexpected litter, probably from some ignoramous people who didn't sex them right or seperate the babies at the right time. I mean, I don't exactly know how easy it is for a pretty young juvenile cavy to get knocked up, but still...

Oh, and now she is 3 months 1 week old, when I adopted her she was 3 months old, and she just came into the shelter several days before I adopted her, so she was 3 months when she arrived there too.

I was also thinking that she could have just become preggo right before coming to the shelter. I just go by the old saying "better to be safe than sorry". I don't mean to sound paranoid...

Guinea Lynx says that sows can become sexually mature at 4-6 weeks, which would be at least a month old, and males can become sexually mature at 3-5 weeks, which is about 1 month. So, the difference between the sexual maturity date for sows and Lilly's age is about 2 months, or 8 weeks, or 9 or 10 weeks.
But we also need to remember that she was there at her original home before she was sexually mature...

Thanks in advance!