Has anyone else experienced this?

I had a miscarriage in November, 5 1/2 weeks pregnant..bled for 2 weeks. Then I had my period in December reg (28 days cycle) in January- February my cycle was 37 days. Now from February to March I'm on 46 days.. With no period yet.. I'm 10 days late with BFNs. My boyfriend and I are ttc again so has anyone gone through this and was still pregnant? I'm having terrible nausea in the morning and excruciating lower back pain that I got the exact same time when I found out I was pregnant.. Any advice will help, thanks in advance :) ❤️