I have three suggestions:
There is a technique called Fartlek, where you simply run as long as you comfortably can (even if it's just a minute or two), then walk until you feel okay, then run again. Do this 3x/week, alternating jogging and walking, for a total of 15 or 20 minutes. Gradually, you'll be able to run longer with fewer breaks.
The ankles are a concern. They can easily be damaged if you run on concrete, run when you are tired, or run with bad form. Do good ankle relaxations and rotations for both warm-up and cool-down.
With the asthma, check with a doctor before running. But go with a doctor who is either a sports-medicine specialist or a running enthusiast, not one who would be afraid to encourage you.
Way back in 1980, the Complete Book of Running got me started - and it's still good!
Take care and enjoy!