Am I pregnant? Period due today but nothing yet.?

My period is due today, but hasn't arrived yet. I already have three children. I have only just started the pill from my last period, but missed two tablets and didn't take it at the same time every day. I kind of felt twinges in my ovaries from the time of ovulation until now. We also had around or before day 14 and I remember having pink discharge after. I just thought it was from the , but perhaps now I think it was implantation?. I had today gooey discharge with a tiny bit of brown and that was it. Have been feeling a little nausea, but not a great deal. Light headed and just feel pregnant. Is it too soon to take a test. I'm not sure If I am ready for a fourth child, but would certainly be excited. What are your thoughts?