Hello and welcome to HCM,
Thank you for your query.
You need to understand that your injury
was unfortunately at the part of the leg that holds you to the ground. If both these bones are weak, they will not be able to hold your body's weight and will thus lead to instability.
I am sure most of the healing has already taken place, but yet, depending on the type of injury you would have either been operated on (placements of a steel plate/rod) or placed with a cast.
In case you were operated on, you need to give enough time for your leg to heal and in case you were only placed on cast you have to give your leg enough time for the formation of the new bony tissue which would help in joining the broken part, thus making it one full one again.
As this is new bony tissue, it will take ample amount of time for it to form and harden, thus, although it might look like the bone unification has taken place, we have to give it time to harden and start carrying your body's weight.
This is the reason why your doctor has advised the leg boot. Please wear it, as it is not really limiting and will give you both stability and confidence in moving around.
You should be able to start walking without it soon, and although your doctor is the best person to decide the duration of use (leg boot), I am guessing 7-10 days minimum, and 2-3 weeks maximum.
I wish you a speedy recovery and great health thereafter.