Help, Any Advice would be great.

So my boyfriend has said to me in the past that he sometimes gets bored with our sex life saying we do the same things. We have been trying new positions occasionally but its sparatic and they are positions I've never done before or dont know how and I feel dumb in the middle of sex being like is this right? and he very lovingly helps me figure it out. I would just want to contribute but I guess I'm not sure how to go about it and I want him to know that I am just as much into him as he is into me. Recently we havent been intimate much related to he works 50hrs a week and I work full time as a nurse and we have a 5month old who we watch all the time. Also currently we can only have sex in the bedroom related to living situations.

Also, another thing is that I can't get off for some reason no matter whatbwe try. and he thinks it's because of him and its not. I am completely into it and satisfied. but it affects his self-esteem mean while I don't mind cuz I'm satisfied. but I'm always so close then nothing happens and just become dry. any tips?