Well, you are back and running which is most of the battle. Symptoms from a big ankle sprain can take months to recede as you are finding.
As for committing yourself downhill, I fully appreciate how you feel. I turned my ankle so many times that I was pretty disabled. Eventually I decided to run in a brace. After trying an arthrex brace (like Andy Murray uses) I eventually discovered the Swiss-O.
Google it. This is a lace up brace which is very slim and easily fits inside your fell shoe. I guarantee you will not notice it at all when racing and it gives you full confidence back. After time, you can eventually stop wearing it if you like although I got so used to mine I stayed with it....putting it on was part of race prep!