After attaining menarche for some months irregular periods
are common and anovulatory cycles are common at that time.
You didn't mention,
Since how many months your periods again became irregular?
What are all the hormones you checked?
If you have recent weight gain and excess hair growth on face etc features the chance of poly cystic ovarian disease
In which anovulation
, irregular periods, hirsutism
like symptoms will present.
There will be elevated androgens, insulin, LH and decreased (SHBG)sex hormone binding globulin.
Other possibility is thyroid abnormalities which will also lead to irregular periods.
Deviry is medroxy progesterone
which will act on estrogen primed endometrium leading to withdrawal bleeding.
Your spotting will subside soon. Hope future cycles will be regular.
If not underlying cause should be treated.