I've been told enough times I am. "Grafted in", most certainly according to the prophets and Yeshua. So you have nothing to be sorry about!
Consider His commandments. Are you sure His word was modified by a handful of bootlickers a coupla thousand years ago? If so, I guess you can call yourself whatever you want. Still, you’ll never make a minyan, and you’ll take His name in vain all your life. It’s a bummer, but it’s a life you’re free to have!