Wendy, I don't know how it works for most people but here's how it went for me.
I lost the first 50 pounds in 16 weeks, so it came off fast at first. The next 50 took five months, though I was just as dedicated and doing all the same things. The last 22 pounds took three more months, so I was losing about 7 pounds a month by the end.
It never got harder really, it just got slower. I mean, it was hard in the sense that I had to be consistent, day in and day out, but by the time I had lost 100 pounds, the eating and exercise were second nature to me. It gets slower for all of us because our smaller bodies need fewer calories, so it becomes much harder to create a calorie deficit at a lower weight. So it's totally normal for weight loss to slow waaaay down as you get to the last 10 or 20 pounds.
You're doing so well!
Keep it up and you'll reach your goal, even if the weight doesn't come off quite so quickly for the second half.