Question...?

Kayla • Married 8-18-18 💜 Furrbaby Mom 🐶🐱🐯 Mommy of a 4 year old princess 💕👑💗
So I quit taking my birth control back in October, my prescription ran out & I have been having car issues/hard to get off work in order to go get a doctors appointment.
I had a regular. In November and December, but now haven't had my period in 6 weeks.
I've taken three pregnancy test, all negative.
My fiancé & I are careful and use condoms.
Anyone else experience this after getting off birth control? How long did it take for your periods to become regular again? Did you have to do anything to restart your periods?
Thanks for all advice!