Not pregnant?

I’m coming here for some help/insight because I’m starting to get worried. I skipped my period last month... while the likelihood of me being pregnant is slim (on birth control, always use condom, plus pull out) I still took a test since it is unusual for me to skip periods. The test was negative. I waited another week and when my period still hadn’t arrived I tested again and the results were still negative. It is time for my period this month and it still hasn’t came. I plan on testing again if it does not come this week... but I’m concerned. I don’t think I’m pregnant but don’t have an explanation to why my period isn’t coming. I have moved to my own apartment in the last 6months and my diet has changed a lot, plus I’ve been going to the gym for around an hour a day where I didn’t go at all before.... I know this can effect your period as well but I’m nervous for my health. Any insight, advice, or similar stories from anyone?