awkward sex talk, please help

Ok so my mum said for me to come to her when I'm ready to have sex because she's worried I'll get pregnant. She said she wants me to be safe and she will buy us protection. ive been going out with my boyfriend from just over 2 years,  I'm only 15 and I keep thinking about doing 'it' with him. He wants to and I do as well but I don't know how to talk to my mum about it as it is awkward and I'm under the legal age. HELP PLEASE!!! 💖