You need to start today. It doesnt make that big of a difference if you dont play a sport, you just need to be social. You say your friends with a bunch of guys who play sports, do you hang out with them over the weekend regularly?
Acually on second though, fvck weekends, do something every day. Spend your time with people. Be kind of random and ask a girl friend if she wants to hang out after school tomarrow, just be playful and random about it and it wont be weird. Dont even worry about gaming her that much, it should start to be coming natural now, the way you act and the things you say will be attractive to her.
If you keep busy with people you wont feel like your wasting your senior year.
As for the virgin thing, it will happen when your able to handle it. You have to know the right moves to get to sex. Be patience it will come. The biggest piece of advice i can give you is location. location, location, location. You will never have sex with a girl if you dont know how to isolate her in a good and confortable sex location. I cant tell you what that place will be becasue it will always be different, you just have to pay attention to the situation your in.
And dont worry about stepping on some feet this year. Its your senior year and you wont see most of these people after you graduate. So what if you make a couple enemies. So what if you let some people know what you really think of them. I let the qb of the football team know what I thought of him at the beginning of the year because I just cant stand how he thinks hes tight sh1t. All I said to him was what everyone else in my grade thinks.
Its your last year so dont be afraid to make a splash when everyone else just makes ripples.