Regardless of whether she is or not, posting her photo is not cool. I'd start by removing it ASAP.

Here's a novel idea, ask her why she has 2 phones, is unavailable Thursday to Sunday and always carries multiple condoms, then weigh her answers up with the laws of probability and decide whether you believe her or not. If not, even if her story turns out to be true then it doesn't really matter, you didn't trust her so don't waste each other's time.