Thanks for the query.
According to your description I am thinking that you are using depo shot for prevention of pregnancy
Usually if you do not take the shot at expected time, complete protection from the pregnancy can not be guaranteed.
And the other things also to be considered are, irregularity in periods is common while being on shot and urine pregnancy test kit may not detect early pregnancy sometimes.
So, you once consult gynecologist, get examined and go for blood test
If the test comes negative, you can take tablets to induce withdrawal bleeding with her advice.
And after starting of the withdrawal bleeding, you can go for some contraceptive
method according to your wish.