Is it normal that i do this when i masturbate?

Just another turn on. Be cool with it. I think it would be very arousing to masturbate with a girl.

hehe, ya, sounds familiar. I am with another girl though(mostly lesbian), and i also sometimes imagine myself as a guy doing her when i masturbate.
I don't actually think this has to do with straight, bi or gay, more with curiosity and assumed gender identity, i think basically everybody already wondered how an orgasm feels for the other sex, no matter their orientation-from there it's only one step further to put oneself into this different "role" and wonder about this sexuality in parallel terms(stimulating oneself and imagining one to be of the other gender).

If I could do it again I would LOVE a woman to watch me when I suck my own cock and cum in my own mouth. But I haven't been able to do that for awhile.

penis envy! very normal

that's perfectly fine.

what matters is that you enjoy it and that it works for you.

so if imagining that helps you get your release i say, lie back and enjoy it to it's fullest

Well said Terry Vie!!