Mrs, do you track your cycles? It would be helpful to know if af came early or ovulation. Not the same thing... Also, if this is your first full cycle since your mc then it can be a bit off and you should probably just ignore it.
LPF, I'm glad your gynae is addressing your bleeding but I don't like his reasoning about four consecutive miscarriages being bad luck. Just because he hasn't found a cause it doesn't mean there isn't one!
I think a referral to a more specialised doctor (i.e. Prof Q) would be more useful than just blindly trying again.
Don't worry about your age and especially not about being respectable in a new job. You'll still qualify for maternity allowance and you can prove your worth/respectability when you go back after. You need to be selfish and put yourself before a perceived view of a possible new employer. Go get that baby!