Sec with Fiance

So, I'm not going to give all the nasty details. I want a baby but sex with him is so.. difficult. I never cum (unless I masturbate) and he doesnt last long. I love him and he loves me and he has tried to spice things up and do better for me but its just.. not working? So now that I want a baby I'm finding it difficult to even have sex since I know how it will turn out. I want to try him "eating" me so I feel good yknow? but I'm also very self conscious about my downstairs lol. He has an average size and he truly will do anything but I feel like it's my fault. y'know? He wants to have a baby and cant wait to start! But I'm always saying "no not today" or making excuses like I dont feel like it or something stupid when all I wanna do is bang. Any advice to help me get my sex confidence up? I wanna try new things but I need to have that voice to do so. Thank you for reading <3