Good luck with your rehab. Do what the Physio tells you and let pain be your guide. Developing good leg strength is really key to your future sporting activities so that should be a priority. The aerobic stuff can’t be developed if you have a bad knee so focus on that now. BUT…Physio comes before strength at this stage: HEALTH BEFORE FITNESS.
The way to tell if you started off to hard is if you are not recovering. You will need to progress the training load/volume if you hope to keep improving. If you are already maxed out time wise and you’ve just started then that is going to be an issue once you begin to regain fitness in a couple of months.