It's tough, but the only person who can put a name on your gende identity (in my opinion) is you. A lot of things you said I can relate to, such as being a tomboy, playing the 'boy' part in pretend games as a child, preferring my relationships to be identified as straight or gay because of how I felt (I'm bi, but when I only dated men I identified as gay, even though I was female-bodied). I only ever wore very tight sports bras myself until I could get my hands on a binding tank. I used to hate it when my partners would try to reciprocate in sexual situations because what I had didn't match with what I felt I should have.

As for whether you would even need to ask yourself, I never knew until I saw a documentary about male-to-female transsexuals at the age of twelve and wondered if that condition could go the other way, too. I was incredibly relieved when I found out that the documentary had named exactly what I felt, and that I wasn't alone.

And the fact is there's a pretty broad spectrum of gender identity under the 'transgender' label, from people who are comfortable with their birth bodies and simply prefer to present as another gender or androgynous to people who undergo full transition with surgeries and hormones, everything in between. I'm not planning to go all the way myself; I don't think it makes me any less of a man. But something that helped me in the beginning was recognizing my boundaries, such as what kind of pronouns I was most comfortable with, and how I wanted to be seen by the world at large. Trying to dig deep and get the full answers about yourself, while difficult, is one of the first big steps in my opinion. Also finding a counselor who is open to gender diversity and won't try to 'fix' what's not broken, and focus more on trying to help you thrive however you need to. There might be a GLBT-friendly or focused counseling center in your town; if there is and you're able, I'd give them a ring.

I don't mean for this to sound like a lecture, being so long. Best of luck.