Well done Herk_man. Regarding the core tests, recommended by neurospast, you should try them again again observe if it is easy to keep your pelvis and trunk still and symmetrical while you move your leg. If you have trouble with any of these then do them as core exercises and then seek assistance re progressing them when you are ready. I still think you should have your muscle balance assessed by a physiotherapist, as, if you have persisting imbalances you will be vulnerable to recurrent injuries.
Keep the concepts in mind that you have mentioned re rest days and gradual building of mileage. Good luck with your event!