Like Icy said, great job Holly! I never thought I would: 1. Want to run or like running. 2. Be able to run for any amount of time.
I've had better success than I would have imagined especially at my weight. I always feel I should mention that getting a HR monitor and keeping in the aerobic zone with a walking/running start made it all possible. It costs a bit, but it has been worth it to me.
Keep it up and hopefully your ankle cooperates. Make sure your shoes have good support and padding. Your ankle is absorbing as much as 3x your bodyweight with each footstrike so padding isn't a luxury. For me that's nearly a thousand pounds of force so my shoes are aptly named "The Beast". They aren't sleek or light, but they are sturdy and well padded. So far, I haven't had much soreness or discomfort and I have a bad ankle, knee, hip , and lower back all on the left side.
It's a catch 22. I'm heavy and I could get lighter by running, but It's hard to run because I'm heavy. Take things slow, make sure you have good shoes, and listen to your body. That' worked for me so far. It sounds like you are headed in the right direction. Good luck!