I feel like im losing her to my friends.. what do I do :'(

I know im young at 15, and im in love with this really nice girl, she loves me back and we both think this is the real deal, we have talked about things before and we know we wanna wait longer before we go to far, we dont wanna mess this up, we have talked about what we want in the future and things like that, we both really wanna last as long as we can.. but as the months go on I feel like I might love her more then she loves me, when shes around my friends she ignores me and I know she has feelings for one of my friends, and thinks a few others are cute.. is she trying to use me to get to them? or will she grow out of this and go back to her friends soon.. in the last few days she wont say “I love you too” when I say I love you to her, but when she has to go she says and and expects me to say it back, I do say it back, but I feel like she thinks she has me so tight that I wont leave her if she gets to involved with my friends.. at first I had no problem with this, but now its everyday after school she will hang out with 6 or 7 of my guy friends for hours after school.. and I know for a fact that she told one of them she has feelings for him.. he said “oh.. im sorry?” and she got so upset.. she wouldnt talk to me and told me not to say I loved her.. what do I do to fix this without hurting us as a couple, or having it seem like im trying to be “controlling” or demanding..