stuck..

Hi guys this might be a little tmi sorry about that, but I have a question which if possible I could do with some advice on that I'm a little embarrassed to go and ask my doctor I must admit. When me and my fiancée are having intercourse, may I just point out that we are trying for a baby, when he ejaculates inside of me, now I know it only takes one tiny sperm to reach my egg, but his sperm doesn't seem to stay inside of me for very long, before you know it his sperm is trickling out of me. I try not to push or move but it just runs out of me like it's not supposed to be in there if you get me. This question might sound silly but we have been trying for 7 months and can't seem to conceive. It's so hard, and I'm trying to pin point as to what it could be and this is the only thing I can come up with. Please help if possible any advice I'm grateful for. Thanks guys x