Are there are any steps I can take to determine if she did have a child and if so, is it mine or not?

I was with my ex roughly 10 years ago. During and towards the end of our relationship, she had told me that she was pregnant. Not knowing how to handle said information, I freaked out so to speak and she later confided that she wasn’t in fact pregnant and that she was only 'testing' me. Needless to say though, our relationship was rocky and tumultuous at best and led to us breaking up. Upon doing so, I did what most people do in that situation and try to get to the root of our problems in hopes of fixing them but by then it was too late and already a lost cause. In doing so though, she once again assured me that she wasn’t pregnant. Fast forward a year or so when I’m walking into a restaurant with my new girlfriend at the time and who did I happen to run into but her. Not only was she much thinner but she wasn’t there alone either. I recognized her mother, father, and a little baby sitting at a table not that far away from our own. Upon talking with her and her unable to look into my eyes, she had stated that the baby was not hers and that she was only babysitting for a friend. Now we have both drifted apart and gone our separate ways losing touch with one another but as you can imagine, that has never sat right with me and I’ve always wondered since if the baby could indeed be mine.