Not really a case of being the 'only girl' since I'm not a girl xD (Sorry about the connotations, I just didn't know how to reference it, etc)
Advice wise, though, I fit into the category of not knowing anyone and such. Never really did and I still don't. So I went at it alone.
Trust me, it'll work out fine as long as you can keep up with the content. You'll probably make some friends too, though I wouldn't know there; help-wise from your teachers, they probably offer extra help because they understand your situation. If they notice that you're alone and don't really get along/talk to other folks as much as other folks might talk to each other, then you'd expect them to offer a little more help that you might otherwise get from other students. It's not a matter of them thinking you necessarily need it, but I'd see it as them trying to make sure to stay open to conversation on the subject and to keep you talkative about it.
That's my two cents, at least.