Forgetting the pills for few weeks, makes it necessary to use other contraception
to avoid pregnancy
If you have had sex some where between 15 to 27 april, you may have concieved.
The symptoms which you are having, however can also be a sign of the eminent start of the due period.
However to get confirmed you need to repeat the pregnancy test, if it is still negative you can wait till your period returns (which may be delayed for a few days). If it doesnt return you should confirm it by an ultrasound
Relax & take care!