What are my chances of getting into UMB Nursing?

I should think your chances would be good. There seems to be a high demand for nurses now, and the population is aging. Significant public health risks seem to be largely ignored, and population is increasing. Your GPA seems pretty good, but I do not know the current state of grade inflation. I think the recommendations will go a long way, and you might go ahead and write up letters for them to sign (though it might be better if they have a letterhead from the recommenders organization). I would say do not retake the TEAS unless they reject you, or tell you the score needs to be higher, or it is free and you are bored. If you have the summer 'free', you might volunteer at a local hospital or nursing home, for something like clinical experience.