Bf doesn’t cum all the time normal?

When my bf and i hav seed he doesn’t cum all the time sometimes he will cum a few days in a row and other times he won’t cum for about a week other times it takes a while for him to cum and then the other fun he came in about 5 minutes. We are trying for a baby and it’s frustrating we tried pre seed today but it didn’t work he didn’t cum. We are going to use some again tomorrow and see if he cums and hopefully it does the trick.