Missed period

Last year April 21st I got my first ever Birth control shot ( worst day of my life ) and Three months later July 15th I got my second shot after three months went by it was time for my 3th shot but I didn't wanna get it because I didn't like how it was making me gain weight I had different mood swings everyday the change in my period I was not happy with it at all so I haven't had a shot since July and i stop having periods since November ! Before November I always seen my periods but since then till today I still haven't had a period and it's been almost 7 months I'm so scared idk what to do I'm not pregnant because I went to the doctor n took two tests already n a blood test n they found nothing wrong with me