I have not gotten periods from last 45 days. In middle I got slight bleeding up to 10 to 15 drops. I had done a pregnancy test also but the result is negative, so please can you suggest to me what should I do?

I think u should see you doctor

There are 100's of reasons for women to miss a period. Sometimes they just miss them due to cycle being off.
It can be infections, STD, stress, illness, hormone imbalance and more.
If you still don't have a period on the next due date, try another test, if still negative, go see your normal doctor to be checked out