I second specialmom.
I've had so many boyfriends that I just "loved" since I was 15. Don't fight over boys. When you're older you'll realize it was ridiculous and that mom was right. (Trust me...I know. lol I've admitted mom was right about teenage boys). My dh and I met when we were 6. We didn't date till we were 20. That's 14 years of growing up and we're still not done. We've been together almost 5 years, married for 2 with w/ 2 year old twins. (I'm dreading the teen years btw...and when you're a mom you will to. lol)
Drop the attitude that is a HUGE thing that can drive a wedge between parents and their children. Just know that your mom wants what's best for you. And as far as sex goes...that is every parents worst nightmare. Knowing their child is sexually active. (I wasn't until I was almost 20) You risk pregnancy, std's, sti's and the broken heart.
And again like speicalmom said...she knows you better than you know yourself.
At 15--------- your number one thing is to do well in school. I know you love your boyfriend------ but can I tell you how many boyfriends I've had since I was 15 that I was deeply, madly in love with? Don't fight with your mother over a boy. Mom's are forever and boys (until you marry) will come and go. You can invite this boy over to your home and let her get to know him. Maybe that will help.
Teen age sexuality is a scary thing to a parent. YOU run the risk of pregnancy, std's and having a broken heart if you become sexually active. The broken heart is usually a sure thing to be honest with you. I'd not be thrilled about such texts and start to wonder what my kid was doing too. Don't give your mom a reason to worry.
And I can't say enough about to the idea of you thinking about how you want to spend your future. I hope you are doing well in school, making plans for further education such as university, and getting a plan together for yourself for what you want to do after the teen age years--------- that will be here sooner than you think. That is the most important thing for a 15 year old girl to think about. Throw in some fun with good girl friends as well. And believe that your mom loves you and wants the best for you and DOES know better than you do. Good luck