Help a virgin out

Hey guys so basically I have been with this guy for 2 years and we are both so happy, I’m currently 15(turning 16 in 2 months) and basically me and my boy have recently began to explore each other, we have spoke about sex a few times as we are both totally comfortable talking about it, we both aren’t in a major rush to do it but we are both starting to kind of wanting to it and we are both ready. I’m scared to ask my mum for birth control so should I just buy condoms the now until I’m 16 n then I will tell start on birth control or do you think I should just go to the doctors and ask for some birth control? No negative comments please I’m just simply asking for help and advice x