I Haven't Had A Regular Period In About 4 Months,

i haven't had a regular period in about 4 months, it comes late, doesn't last as long and is lighter than normal. Over the last few weeks I have been feeling twinges in my stomach, but I shrugged it off. Now the twinges we a lot stronger and my husband can feel it too. I've taken home pregnancy tests 3 times now and they were all negative. Could I be pregnant or is it something else?