You have my sympathies Nells - I'm now two months into my longest every layoff from running due to peroneal tendonitis, and I've been going stir crazy through not being able to run for so long.
I have just these past two weeks taken a few very tentative run/walk sessions, and like you was extremely nervous about how my injured ankle would react.
Although things have gone better than I hoped they would, I'm by no means out of the woods yet so will still take baby beginner steps for another couple of weeks.
I have been able to keep my CV fitness in check by cross training, cycling, lifting weights, etc... but nothing beats the joy of running for me. I shall keep reminding myself that I have my whole life to run, just in case I start thinking that I'm completely better and end up doing too much too soon, thus re-injuring myself.
My best advice would be one small step at a time - take it slow and steady, listen to what your body is telling you, and please don't be too disheartened if you feel as if you are a beginner all over again. It will come in time.
I wish you the best in your recovery - and fully understand your frustrations. You are not alone in this, believe me!