How long after the injury did you receive any physiotherapy?
It may be that the scar tissue around the site of the sprain is limiting your range. Your ankle needs what is called an 'accessory glide' to move through full range. This can sometimes be limited following injury, so your physio might need to do some work to normalise this using frictions on the scarring site and possibly some AP glides of your tibia? Keep us updated with how you are getting on!