Consuming a pill in November does not affect your cycles for so long; also you had regular cycles for a while after that and so pill effect is ruled out. The cause of your present state of irregular cycles could be a collective hormonal
imbalance probably induced by hormone use for changing the cycle rhythm. Since you had protected intercourse
and that too without ejaculation, your chances of pregnancy
are less. Yet, since it happened around your ovulation time, you need to exclude pregnancy. As you had a negative test on one occasion, you may repeat it after a few days or better still go for the blood test
. Consult your health care provider for further support. Take care.