What Causes Sudden Cravings For Ice Cream, Irregular Periods And Weight Gain?

I am a female. The last time I had sex was the end of January, beginning of February while I was on the last day of my period. A week later I had a light spotting when I wiped only. About 3 weeks later, I had two days where I woke up and had sickness in the morning. My period came 3 days late and was very light. I went to the hospital and they gave me a pregnancy test which came out negative, but they told me sometimes its too early to really tell. A week and half after that period I got another period which lated 5 days but was very very light. I usually have complete 28 day periods with heavy bleeding. It s been about 2 weeks since all that and some days I wake up feeling sick, I have been much more tired lately, and have been craving cold foods such as popsicles and ice cream which is not like me at all. I have gained about 7 pounds and my hips are getting wider. Could I be pregnant?