how to get pregnant.

I had a miscarriage back in 2016 and ever since I've been struggling to become pregnant, I've had a lot of pregnancy signs recently especially very dark nipples my period is also 2 days late now. I have been having mild cramps and had implantation or spotting on Sunday last week, been going toilet loads, no sign of period as I get loads of pain and cervix is always low before period is due but my cervix is high firm and slightly open so not sure what's happening.. My cycle is every 28 days so I'm not sure. I tested but negative xx