Sampling of trich
Well trich can be 'tricky' if I can make such a pun.
The issue could be with the quality of the testing... so if your male partner is testing negative, it might be that either a) he didn't have it or b) the sample collected was not sufficient. It could also be that in your case c) perhaps it wasn't trich. I've seen that on rare occasions. Best thing to do is talk to your doc- maybe a couples visit