Unknown current email address

i lost id apple. i just have rescue email, name user, some free app in app store and don't have buy any stuff in iTunes.

i don't change primary email but someone could changed primary email somehow. How i know the current email address if primary email has changed to prior?

in this https://iforgot.apple.com/appleid ,they may be not support the true owner of id apple cause i cannot known current email address for find id apple.