70 Day Cycle Anddd Counting !!!

Sooo I'm About 18 Years Old Now And I Started Having Periods At 14 And My Periods Are Alwayssss Irregular, Whether The Length Is 10 Days Or I'm Skipping Months. Sooo I Was On The Depo Provera Shot And It Was Just Torturous Side Effects Sooo I Stopped Taking It In June. After That My Body Was Back To Normal And Periods Were Much More Normal Than Usual. Then Last Month I Noticed My Period Was Late And I Took A Test-Negative It Was So The Following Week And The Week After I Took Tests. All Negative And Even Last Week Went To The Doctor. Sooooo If Its Not pregnancy Then Ik It Could Be Many Other Things 😢😩 I'm Really Worried. Should I Be Worried ????? Help Anyone