I’m having symptoms but my tests keep coming back negative

Hi I need some help I’ve trying to get pregnant. I came off the pill about 6 months ago and my periods starting up again after 3. Ive tried every time I’ve ovulated and came on my period every time. But this month I feel a bit different I feel sick and gone off food, I have sore breasts and now Im 5 days late. I took a test on the Thursday (first day I didn’t come on my period) and it was negative. I don’t know if I’m being stupid but could I be pregnant? Could the test be wrong?