Irregular

I've been ttc for about four months now, and its so hard. I'm irregular as well, and the past two months, my period would come 2-3 days later after the previous one. Also, my period i haf last month was very light and lasted for only four days, then two days after i ended my peeiod, i started having some spotting, now i started my period yesterday, and it started to be heavy and i had extremely bad cramps all day long, which i never had cramps this bad either. My sister said i could maybe still be pregnant, and my friend said i could be too.... But...It gets my hopes up and gets me a little depressed. Could i be pregnant still? If not, does anyone have advice on helping me have a better chance of getting pregnant?