I'm posting here as this is the only place I feel safe sharing this.
Basically, I'm pretty sure I'm FTM, after quite a few months of thinking deeply and suddenly a lot of things in my life make a bit/lot more sense.
I have sort of told my parents, not in the way I'd like (I was having a discussion with them after going to the doctors for depression and being prescribed antidepressants, and they asked if I had a 'sexuality issue' and I sort of told them about my feelings towards my gender, but they didn't really understand) but my mums burying her head in the sand and ignoring it, and my dad is a bit more understanding, but his opinions can change drastically, particularly when he's angry.
No one at my 6th form knows, my best friend doesn't, no teachers, no one.
Anyway, I planned on talking to the lady I see for councelling every Wednesday, and possibly going back to the doctors early, to talk to her about it, but I'm too scared to tell anyone else, without them bringing it up first, especially as I don't really know how I feel.

But something has happened and I now don't know what to do.
A boy in my class who I've been talking with for about a month has said he wants to go out with me, and I said yes, as I didn't want to make him feel awkward.
But, everytime I think about hugging or kissing or even holding hands or anything, I just freak out and constantly feel on the edge of a panic attack. I don't really know if I feel attraction to people, or just envy of male bodies. :/
I've never had a boyfriend, never even wanted one, but he asked me this yesterday and now I'm just freaking out.

I've mentioned to my best friend abut getting my hair cut short, and she supports me,  and she's said she'll go with me to try and find some boys jeans to fit me, but she doesn't know about my feelings, she just thinks I'm a tomboy.
Also, if I got my hair cut, it's likely he would be weirded out and make everything more awkward, and the guys in the class would say something.

I'm wondering if I should mention all this to my parents (but then I'd have to tell them about being asked out), or to my doctor, or just tell my friend but I'm worried everyone will hate me and I'll be left with no one.
The only person I feel I could tell is the councellor, but I don't know where I'd go from there :/
I'm worried I'm not actually transgender and I'm just being stupid, but I don't know.

He's said we can 'take things slow' but I just think I'll have a panic attack or something, just going in on Monday, in front of the entire class of guys and my friend. 

I don't know what to do, I just know I can't be someone's girlfriend.
Please give me some advice> 

Tom. (I feel comfortable being called this)

Well I tell you my opinion... its up to you what you do...

concerning the friend asking you out you might say you want to stay friends for now... nothing more...
concerning your female friend you could tell her the truth... that it makes you uncomfortable being with the boy asking you out...

concerning clothing I'd say its a good idea. It might help you see how you feel.
Well many people are versatile now so you might say its your style and you feel comfortable this way.

here are a few resources on coming out:
https://www.susans.org/forums/index.php/topic,197598.msg1757491.html#msg1757491

and here are a few resources for self exploration:
https://www.susans.org/forums/index.php/topic,194986.msg1737439.html#msg1737439

Basically you can talk to your counselor, telling how you feel and maybe showing a brochure...
and asking for a referral to a gender therapist...

same at home... you might say you want a good gender therapist to help you along.


*hugs*

My advice is to really look at the consequences that could happen if you go to your counselor. Do you think they'll tell your parents behind your back or react in an unprofessional way? If not, then it's probably your safest place to try and get more helpful advice about your feelings. Plus it'd be a way to open up how you feel uncomfortable with that boy asking you out, and you could also get a professional opinion about that.

When it comes to the boy who asked you out, if you really feel discomfort just at the mere idea of dating him, you might wanna try pulling him off to the side alone and telling him you're actually not ready for a relationship at all. Being polite will make this easier to get through but whatever means necessary for your own comfort. (if you can't face him in person, try messaging over fb, kik, skype, or whatever social media you have)

The fact that your friend seems really supportive about your clothing/hair/etc. choices, is a good indicator they'll continue being that good friend towards you even if you tell them. However, just to get an idea, maybe bring up something trans related in the news and ask their opinion. You can see how they feel about the subject and go from there.

Also don't fear people talking about the outer changes you make, because you won't live with having to deal with these people's opinions forever- and they'll get used to it!

On a more personal note, I feel you with the whole "I can't really tell if I am, or I'm not", however, a lot of people on thee forums have told me they've have spells where they thought they weren't trans, and then they were confident they were. It's a constant battle of both sides sometimes, but time will certainly reveal more.

Sorry for my very long answer, I hope some of this was help to you!!