It can be hard to know.

It's also important to ask why you want to know if you have PTSD or not? Will knowing your diagnosis help you to better cope with the stress that you experience, do you hope to recover the memories, etc.

I have chunks of memory missing but I can remember my parent's domestic abuse of each other. I'm guessing this is my traumatic experience. I was diagnosed with this while I was in the hospital and I still don't fully accept the diagnosis. It doesn't make much sense to me and as far as I'm concerned I'm missing some of the necessary symptoms of the diagnosis.

However in wanting to know 'do I have' I personally find it necessary to ask yourself why you want to know.