Hi Jan welcome. They say a normal healthy couple will conceive within 12months of TTC (not that this helps). You're a little older this time round (not sure how old you are as such but obviously not as young as last time you conceived iykwim). Sometimes it just takes a little longer but the spotting from 21days is somewhat odd. If you're really concerned you can ask to see a specialist. They will check your hormones through out your cycle and maybe a seman analysis on your OH.
In our case we've been TTC for 3 years now but tests have shown I have PCOS, blocked right tube and DH sperm are only half normal lol (to lazy to ask for directions basically).