Hi Jo, it's great that you have no pain whilst sitting. Perhaps you can call your GP about the pain whilst on the move. It is still very early days for you and if you have any pain or discomfort when walking then it is advisable to use both crutches when walking as you obviously need them. Try not to compare your recovery with anyone elses....I know that is difficult to do but we are all so different and heal at different rates. The crutches are there to help protect your new hardware while it settles in, to help with your walking and pain level. If you have pain when walking with no or only one aid then your body is telling you that it is not ready for that just yet. Hobbling along without the crutches is not the best thing to do.
Some of us are off the crutches within a couple of weeks, some months. It is best to use them when necessary as you don't want to get into the habit of limping and the crutches help you not to limp. I know it is hard as we just want rid of them but it's a game of patience these first couple of weeks/months but it is well worth it
As for the longer operated leg, this is very common, pretty much all of us had that occur after surgery. It will go back once things settle down, could take quite a few weeks but it will get better. You still have a heck of a lot of healing going on.
Take care, it does get much better, I promise you
Ann