Debi,
Marge is dead right - it takes time to progress. It's natural to be impatient and want to see immediate results, but be patient and enjoy it!
One thing you might try, instead of increasing run and walk time together, is to decrease your walk time slightly/gradually.
Faster runners will usually do interval sessions once or twice a week - alternating fast bursts with slow recovery periods, and play with increasing the number of repetitions and adjusting the time ratio of effort to recovery. I see no reason why this shouldn't work for you, albeit at perhaps a slightly slower pace!
I can't add anything regarding medication, but Philip seems to make sense to me. Have a word with your GP and see what s/he suggests.
Above all, try not to get disheartened - progress will come!

Hi Debi,i too struggle with breathing when run/jogs but as soon as slow to steady walk 4mph breathing eases,when i started to take up exercise only managed to reach the end of my road.Started in back end dec 2010,walking with jogs short distances,covered 270 miles this year,furthest distance so far without stopping 1 mile,have managed a few long distances 8-13.5 mile mainly walking.,entered my first half marathon(walking),12th june St.Albans.Been to see GP who has put me on Ventolin and Seretide pumps,try these for a month and evaluate whether any improvement to condition.I am determined to succeed as i have also entered the ballot for next years london marathon,it is very frustrating to find myself a few months down the line,and i am still struggling with breathing and runninng,but determined to beat it!.Also my previous history of smoking and being overweight has not helped,.Have faith in your training and eventually be able to reach our goals :)  (fingers crossed).Be lucky.