Welcome newbies but sorry you find yourselves here.
bumble, good luck for the scan!
flen, sorry you are spotting again. I just wish it would stop for you 
brummie, glad the scan was ok. I have also had loop diathermy so i will probably have to have mine checked too.
paws, implantation bleeding can be any colour, so could be, just have to wait and see! Frer are the best. Don't even bother with ic until you're about 12dpo
loopy, nk cells can vary up and down. It's the reason the profs haven't given this 'condition' a name, because it's an over reaction of the natural state that can come and go. It is absolutely not dependent on whether you've had children or not. Maybe it's worth thinking about, as your pattern is very similar to mine (and i have a child) and I have high nk. The prof also advocates just keeping going with the early ones, and eventually you'll find a good one. It's so hard to keep going though. I know they say 2 full cycles since mc before you can do coventry, but i went after 1 cycle after a chemical (so during the 2nd cycle) . I had long cycles anyway, so it was 2 clear months by the time i went (was a bit ambiguous whether it had to be 2 months or two cycles).
Someone else was talking about nk cells and normal embryos. Under the Coventry theory, the ill prepared uterus causes both non viable eggs to implant, but also causes issues with the implantation process for viable eggs, meaning the placenta doesn't form correctly and causes mc, normally slightly later ones after a hb has been seen and often around the time the placenta takes over, as it can't cope with the extra stress of the blood flow . So you might expect both normal and abnormal results from chromosome testing.
mrsb, i would be pushing for some testing if you can. I find it strange that the midwife had said it's just bad luck because the chromosomes were normal. Actually there is a correlation between more mcs and more normal embryos (ie the more mcs you have, the more likely they are to be chromosomally normal, as there is probably some other cause). I would have thought she'd have used the 'just bad luck' line to explain a chromosomal issue rather than a lack of one. By saying this i don't mean to scare you that something is wrong, it absolutely still could be just bad luck, but if you get a chance to rule out some of the common simple things then it may help you in trying again.
I would also advocate acupuncture for regulating cycles. Mine went from 32-38 days down to bang on 28 with acupuncture. I agree that the most important thing is the luteal phase being long enough, but a longer follicular phase is not ideal (though by no means a deal breaker)
patience, glad your dp had been there for you and hope the d&c goes smoothly xx
I'm sure I've missed some people. Waves to everyone else x