Cramping for over a week and still no period and BFN

I'm a little frustrated on day 42 of my cycle.  Got another BFN. Longest cycle I've ever had.  Last month I did have a 38 day(which was a couple of days later then normal) so might just be getting longer cycles.  The weird thing is I've been having cramps like I'm going to start for over a week.  Other PMS symptoms starting before that.  I'd love for a BFP but if not I'm just ready for my AF.  At what point do I stop taking tests? Accept that maybe I'm skipping my period? Or do I need to get in to my OB to get a blood test?  I do have PCOS.