Missed period

I am super nervous because I haven't had my period in 3 almost 4 months and I have never been this irregular! I'm a virgin so I couldn't be pregnant and I haven't been feeling any pains or anything. I feel like this is kind of normal to happen occasionally but I'm scared there is something wrong with me. Have any of you experienced this and do you think I should go to the obgyn to get it checked out? I'm 20 by the way!