Hi Lauren- absolutely! I think if you stick with training, you'll absolutely be able to pick up your distance and speed. I've run the Pittsburgh half twice, its such a great race. Since you live in Pittsburgh you know better than anyone that you'll need to add some hill training to your schedule since that city is not flat and there is a big hill near mile 11-12. The second time I ran the race I was coming off a foot injury and did a lot of walking. I finished in 3 hours and 11 minutes. There were still a fair amount of people who were running and walking with me. I'd check out some run/walk training programs if you think that is your best way to finish the race. I know there are a lot of people who swear by a run a few minutes, walk a minute, repeat.
I may see in you Pittsburgh, that is the marathon I'm hoping to register for!!!