missed period

Mitzi
Hello, I want someone's opinion  on this. The last time I had sex was July 10th then I got my period at the end of July and August but missed it September. It's now mid October and I still haven't gotten it. I had sex again September 26th but every time we have sex we use protection! I toke a pregnancy test last week and it came out negative. If I was pregnant I would already be feeling symptoms wouldn't I? And it would've already shown?