I Need A General Opinion On What You Think Could

I need a general opinion on what you think could be the cause of my delayed period. I'm 18 and sexually active my period was always on time until the beginning of last year it skipped every other month for a while then seemed to return to normal. I haven't had my period now for two months straight (I know what you're thinking, I've already taken tests and they all came back negative). Here's the doozy I can't go see my obgyn because my mom doesn't know I'm sexually active hence why I'm here. I've read online that pregnancy causes the cervix to rise up higher in the vagina but mine is low and hard.

What do you think could be wrong with me.