What Does Light Periods With HPT Negative Mean?

I am married since last 1 year. we are planning for a baby since last 2 months. This time I got my periods 12 days late and they are not that normal. I mean during night there is no bleeding. during day also its very less compared to normal. I also got checked for pregnancy at home. But it was negative. but i feel very sleepy and restless. so is it that i may be pregnant but it didnot get detected through preg check kit?please help.