There's definitely a chance that you could still be pregnant, but since the test is negative and your period is late, I would say the chances are slim.
Let's say that spotting was implantation bleeding, and it occurred, according to the dates you're giving me, around March 16th. You should have been able to get an accurate pregnancy test around March 18th or 19th at the earliest, but by March 25th you should have almost certainly had a positive test IF the spotting was implantation.
Now, maybe it wasn't. Maybe it was something else and you had implantation later on, then it's possible that your body still hasn't sent out the pregnancy hormone required for an HPT to turn positive.
My best advice is to test again on the 27th. Test again every other day or until your period shows up. If you end up more than two weeks late call your doctor and ask for a blood pregnancy test. If that comes back negative then you and your doctor can talk about other things that could be causing your period to be late.
Almost always, a late period is not severe, and easy to troubleshoot.