Should I tell my gramma?

Hi! So ive been dating my boyfriend for 4 months in May. He is my first boyfriend ever. I'm 14 years old, I'll be 15 in fall. I'm mature and get good grades and everything. Anyways, I want to tell my gramma about him. I'm really close with my gramma and I see her every Monday. She's one of my favorite.people in the world but shes old fashioned. My mom said early on in my relationship with him not to tell her because she would call my mom and be like "did you know your daughter has a boyfriend, have you met his parents, have you met him, does she know about sex?" But now it's been 4ish months and I dont know if I even should approach the subject of dating him with her or even how to tell her. I just need advice thanks.