Worried about her being pregnant?

me and my girlfriend had unprotected sex but I know I pulled out before i ejaculated because i pull out and i have to get myself to ejaculate either by oral sex or some other method, but my girlfriend had a bit of spotting 5 days after we had sex last, it is right in between her periods and she only has one ovary and she has spotted before, and recently had her period. I dont believe she is pregnant but we're still a little worried. We think the spotting is due to her changing her diet so drastically and immediately starting vigorous work outs. But we just arent sure, thank you for any advice or answers and sorry if i offended anyone by using incorrect terms lol