Trust with boyfriend

How can I get my mom to trust my boyfriend and I to be alone in a room together

Well you have to take it slow. I dont think I would be letting my daughters b/f in her room (when shes old enough to have one lol) until I knew that I could trust them to behave in a decent fashion. If you invite him over and she can get to know him then that would be good. Also ask her if he can stay over but sleep in another room and stuff like that so she can see your trustworthy. If my daughter came to me and said mum we want to have sex etc then I would take her to get birth control and have a talk to them (embarassing I know) and go from there. I would much rather know whats going on with them than not and maybe your mum feels that way too?