The same thing actually happened friends of ours. They did one successful IVF that ended in a M/C, then a failed FET and they conceived naturally a few months ago while on a break.
OMG That is such great news!!! Im soooo happy for you!! My husband and I are on a break and Dr. B told us to keep trying on our own since there is no reason why it can't happen on our own! This post made me sooo happy! We needed some great positive news!