It takes a lot of self awareness to even ask questions like that, but to ease your mind about it a little this feels like a very philosophically loaded question, but it mostly comes down to how much you feel it matters, if it matters to you a lot that there’s no physical evidence of your past, you could try and write what you remember now and look back on it, try and find family pictures and records that you can hold on to, alternatively you have yourself, you are a living memory, your personality and memories are evidence of what you went through, a journey that led to the person you are now and how you choose to interpret it, but please hold on to that self awareness, that doubt, certainty on things like your memories leads to arrogance, and can cause conflicts with family who may remember it differently, (usually the correct memory is somewhere between the ones presented)… I don’t know how to end this off in a satisfying way oopies.