I'm 15, why can I never win when I disagree with my mom? What can I do?

She is great, we have a wonderful relationship. The word I that describes my mom is simply love, true, unconditional love. Like most moms like that, she is however overprotective and sometimes I wish I could make my own decisions. Sometimes I do'nt gree w/ her, and even other parents say sometimes she goes oveboard w/ her protection. But since I am maybe weak, I never succeed, I don't fight, she wins me w/ her love and sweetness. She has a tactic that always work. When we disagree on something and she sees that's really bothering me, she comes to y bedside at night and with her love and sweet words explain to me her decision. I want your best hun, I love you I'm more experienced, please trust me. I guess she won't back off, but anyway that love takes my anger away and even if I don't agree I end up promising her, w/ all my love, as she asks me, tghat I'll do as she wants. So, I'm defeated, and once I prmise I won't break the promise. I never get resentful, bt sometimes I'd like to win