The short answer is yes, as i was the same myself with my last pregnancy. It could always be something else so i would recommened that you go back to see your doctor, explain the situation and ask what can be done about it. You'll find that they'll get you an answer very quickly. Hope this helps
of course you can be pregnant. it is possible you had the test done too soon and your hormones were not high enough. when was your last period? (not counting bleeding for a couple of hours this month) are you having any pregnancy symptoms? lightheaded, fatigue, nauseous, frequent urination. i would go buy a home pregnancy test and see what it says now. have your periods always been regular? there are other reasons a women can miss a period besides pregnancy, weight change, exercise, stress.. etc.