I need my phone back

Destiny
During freshman year ( I will soon be a junior) I got my phone taken for 7 months for smoking weed. This past November I got it back and 2 weeks later my mom took it away when she went through it and found out I was having sex with my ex boyfriend.👈🏾(big regret) She never met him and when she asked to tell her where he lived I refused. Now I'm in a new relationship with a good guy and he and my parents know each other very and like each other. It took her a while for her to trust me and let me get into another relationship.., She knows that we aren't having sex and trust us to hang out alone. Why can't she trust me with a phone? It's been too long and I'm almost 17! I need my phone back 😩 Any advice on how to get it back? Last time I asked when I would get it back and she said never...