Amanda - I'm very sorry to hear of your current circumstances. You're absolutely right that you and your son's health and welfare must come first and it sounds like you're doing whatever you can to ensure you're both taken care of. Items such as running shoes - which no matter how you dice it are not cheap - can come when things turn in a more favorable direction. I'm very glad you're not having issues with the current shoes - that is always a good thing!
I'm currently 40lbs overweight, have been for a while (overweight, I mean - the 40lbs is an improvement over the last month or so!) and I run anyway. For sure losing some of the weight will allow me to run faster, probably with better form, and undoubtedly will help reduce the strain on my knees, but I run because I love it and it's the only cardio I'll do with any consistency.
I didn't do the formal C25k plan, but I did something similar with the walking breaks. I think the key to starting any program is to do it at your pace - the worst thing is to have a set back because you went too hard too soon and either hurt yourself or found it unbearably hard (speaking from experience here!). The C25k plan is excellent, and if you find yourself at the end of a week really thinking "I'm just not ready to move on yet" - just repeat the week. It'll work no matter how long you spend doing it!
On your gait, if you roll onto the outer edges of your feet, yes, you are a supinator. Much less common than over-pronation but still something a lot of runners have. It's your natural gait and while you can correct it somewhat with the right shoes, I wouldn't try and completely correct it. Part of my knee issue was due to someone incorrectly determining I pronate and putting me in stability shoes, which then overcorrected my LACK of pronation. Once I got the new neutral shoes, I am finding it far easier to run with a more natural stride. Again, not at this moment in time but when you are ready, see if you can find a running store who can really take the time to analyze your stride and help you find the best shoe for you. You will likely be amazed how being in the correct technical shoe will help you feel and perform better.
And on a final note - funny that you mention getting back on the horse, because that's also something I've just been able to do, literally. I have a horse and had to avoid riding for three months after the surgery - that was so miserable for me, as I truly missed being with my big ol' nag, but now I'm back to riding and running and it makes the days just that little bit better!
Good luck with everything!
