stopped depo & period already?

[nj13]

I was supposed to receive depo shot 2 days ago I never went as I'm having some side effects but woke up today with some bleeding!
Its quite heavy and I'm having bad cramps too.

Iv been on and off depo for 8 years and never had this before has anyone had this experience? And does this mean my fertilitys back?

Little bit worried as I haven't decided which contraception I'm going to use now and thought I may have had few weeks/months to decide.
Any info would be great :)thanks