Still so far to go

Tonight after work, I went for a 45 minute easy run, well so the training plan says it should be. In the time I completed 6 km, monitoring my pace to 7 min/k. All was fine for about 4.5 km and then I fell to pieces, my pins and needles kicked it around 35 minutes as it always does and I was desperate for the end to come and when it did I could hardly stand upright.

I am now looking at the calendar and with only 9 weeks to go until the half marathon and wondering how if I cannot run 4 miles without dying how do i add another 9 to make the 13 I need to cover on the day.