I posted a few weeks ago about coming off norethisterone and not having a period but I still have no period and am now really worrying. I was on norethisterone for 9 months and had 2 breaks whilst on it. Each time I came on heavily 3 days after stopping it. I'm now 3 weeks late, have done 2 home pregnancy tests and the GP has done one too, all negative. In the meantime I have dislocated my knee cap and been on mega pain killers. I've now read in the leaflet for norethisterone that it can interfere with test results, it doesn't say which tests. Does anyone know if it can affect a pregnancy test? I'm really worried as obviously I shouldn't be taking tramadol or co-codamol if I am pregnant! I don't feel pregnant if you know what I mean, I just feel nothing....it's weird, I was expecting loads of pain and a really heavy flow but zilch, naddah....anyone??