Sorry to hear about your problem! To be honest I haven't heard of that before - that it could take 6 months to get your period after coming off the pill. I would agree that can be the case with depo but in my opinion would be fairly uncommon with the pill. It is common to have irregular periods for awhile definitely, however I came off the mini pill after being on it for 12 years and got my period at the normal time.
Hope it all works out and your cycles come back soon! (or you get UTD)