2wks between cycles wtf???

we arnt ttc right now but are planning to in the not too distant future as my ticker.

I had my last baby in January and had the depo jab when he was 4wks a week later i had some spotting but nothing major and put it down to mild reaction to depo or just last of lochia(sp).
I had no bleeding what so ever for 4mths after that.
I got mirena put in and had what i was told was normal spotting a few days later. 12days after getting mirena it came out(on its own) i rang the nurse of the dr that did it was just told it proberbly isnt right for me and nothing else. that was in june. since then i have had af every other week.
i didnt mind at first as i thought at least im not pregnant and i did an HPT to rule it out anyway though i havent done one recently.
i keep thinking ill go to the doctor but then it stops and i think 'ill wait it out and see if it changes' but it hasnt. the bleeding it self is what a normal af would be its just much to short for a normal cycle, and i am sick of buying tampons all the time.
b4 having my last baby my cycles were too long...
i conceived my last baby on CD40.

i didnt pay for it as it was funded.
i was offered a replacement but decided it wasnt for me I hated the wires put me and dh right off BDing