Thank you for your query.
With birth control, it is sometimes possible to have a very slight / scanty period with almost nil bleeding.
Cramping also could be reason for that.
As your home pregnancy
test was negative, chances are very rare that you might be pregnant.
Rarely, home kits fail to show up an early pregnancy or an ectopic pregnancy ( pregnancy outside the uterus ), so that possibility exists.
Also, you might be having altered period due to stress, anxiety, weight loss
or weight gain, emotional trauma, travelling.
and polycystic ovaries
are common reasons.
Contact your healthcare provider for proper diagnosis.