Where is my period? I need help with this please

Patient: I have been on the pill for longer than 2 years now and i have gotten my period regularly i have done the occasional miss of the period but last month i took my pill normally and i did not get my period i was a bit frightened so i took a pregnancy test and it came back negative so i was really happy with those results. i am now up to my period after my last one didn’t come and i usually get it today or tomorrow but i am really scared it wont come. i need advice on what i should be worrying about! Please help!

Symptoms: Mood swings