Period Missing for over 2 months..

My period has been missing for over 2 months and I went to the doctor 3 weeks ago but they said to come back if I passed another month since my visit. This is my first time of it being so late. Earlier on in the year I was on bc then ran out in February, never was able to get a refill. My boyfriend and I haven’t done it since for about a month and 2 weeks but we use protection.. I’ve also taken about 4 pregnancy tests and they’re all negative.. I’m 21 years old and I’m starting to get worried.. Could anyone offer some help or suggestions..?