Anxiety While thinking of a relationship

Hi ! It's been 14 days today.. and life is soo much better with PMO gone.. I'm kinda 17. And PMO was around from when I was around 11. So, since the PMO gone, and my social interactions getting better.. This girl proposed me. I immediately said yes, but the next day I was full of anxiety up to the brim.. I wanted to be with her.. Next day, I went out with her on a walk and it felt good but my rational decision making was gone. I was taking decisions irrationallly and some of the them turned really bad. Following this I backed out. I felt quite a relief after that... but after 3 days, I was aching again for her.. and whenever I did think of her.. I am feeling this anxiety.. from my foot to the head. My legs and hands are shaking and I can't think properly, palms are sweaty too.. I want to be with her.. because 1, she was really into me.. and She's nice.. and This is my last year of High School.. So I don't want to be single either... but this anxiety has been making me go wild.. I can't think.. I have not been able to study... My exams are from next week.. I am afraid If I delay any longer she'll lose interest in me. The problem is this anxiety, I feel relieved when I quit thinking about her... but I don't want to miss this chance either. PLEASE HELP