15 months after my first. Lost that one too, started clomid, took another 7 months, had a chemical, did one natural cycle then a 7th round of clomid and managed to get my next bfp with that one.
I had also been told you can be more fertile afterwards but I wasn't, each mc really messed with my cycles and made them even more erratic than usual (bar the chemical, which didn't seem to affect my cycle too much at all). It seems to really vary and I think I was fairly unlucky.