Help, Baby Blues!

My partner and I are trying for a baby, we have been having unprotected sex for 10 months with a 5 week gap in the middle when I was away with work..so therefore almost 9 months of trying! I have not got pregnant yet! Is this normal? I heard that each time you have unprotected sex there is an 85% chance of becoming pregnant, we usually have sex with my partner ejaculating in me around 7-10 times a week…this is quite a lot in my opinion and so i cant understand why i haven’t become pregnant yet! My boyfriend has a child with a previous partner so I know it’s not a problem with him! I havent said anything to anyone as I dont want to sound silly but it’s really starting to worry me.. every month when my period comes around i feel like crying when it comes! I mean how long should I expect to be trying? Is there a time when I should think it’s been too long and consult a doctor? I want a family and the thought of not being able to have one is tearing me up! I also knwo how much having a family means to my boyfriend. Any advice would be gratefull appreciated as I cannot seem to get the subject out of my head