Does it make me gay to like to wear girl underwear and use a dildo

You said yourself you're only attracted to women. That makes you straight. If you like being fucked in the ass by a dildo which is being used by a woman, that's called pegging. It's not gay, it's just kinky.

Have sex with a transsexual, it's the best of both worlds.

Not really, but it doesn't make you any straighter lol. The dildo thing makes me think you might be a little bi curious.

If you got a vagina from plastic surgery than it's fine

Well, if you like to dress up, too - you might be thinking you see yourself as a female and want to have sex as a female would and that would explain the dildos. It's fairly classic SISSY behavior. Some men have desires to be feminized or sissified, and in that role play being penetrated in your bottom with a dildo would simulate the act of a woman being penetrated with a penis. Do some internet searches and see what you can learn about being feminized or being a sissy. You might learn somethings that will explain your longing. Best of luck.

Hope this helps.

No, you're not gay. If you desire women or are attracted to women then you are not gay. This doesn't mean you're weird or perverted, either. Actually, men have been interested in women's underwear for centuries. There's documented reports dating back to the middle ages of men desiring to see, feel, smell, lick, wear and be adorned in all types of women's undergarments - bras, panties, stockings, garter belts, panty hose, girdles..... even socks, corsetts..... you name it, if a woman can wear it, men have wanted it, too, and they've used it as sexual stimulation, as well. What you and I might know as a "Panty Fetish" is one of the most common unspoken desires many men have. It's quite common.

I am a little concerned that you might not be of adult age and are using dildos (I assume in your bottom). I could understand fingers or other small items if you are under 18 (or so), but if you're actually using dildos and not gay, then I think that's more of a submissive or sissy behavior.

There's no real harm in touching yourself back there. It's understandably pleasurable and as long as you observe some common sense rules about playing clean, you should be fine.

Hope this helps.

Youre as queer as a 3 dollar bill