Ttc rainbow baby #1... Looking for advice pls

My boyfriend and I just lost our second child(I had a miscarriage a year ago) she was born at 20 weeks gest. and I was given ok by de to start trying again this month. My last af was feb 9-13(this was first period after having my baby) I had + ovulation tests feb 24-26. I had some red/pink spotting March 4 followed by brown spotting until the 8th. I was due for af the 9th but still nothing.. I've taken hpt's but always get a negative. I had some nausea last week and have been way more tired than usual but no symptoms like I had when I found out I was pregnant before. Any advice please?