First off, it's not because you're "loose." Semen is going to come out no matter how "tight" you are.
We don't begin to consider fertility issue until a year has passed without success. When/IF that time comes, both of you need to see a fertility doctor. You can expect a full physical, including internal exam and blood work. Your partner can also expect a sperm count.
It doesn't have to be you, it could be him, or it could be a combination. Sometimes there are genetic problems.
Having irregular periods may also contribute to difficulty getting pregnant.
I'm a bit bothered by your partners comment about you being "loose." Tell him if he could shoot it in further it wouldn't come out. It still will come out but maybe it'll make him think about what he says in the future.
Hope it helps.