if you're starting out at 172 and want to be 125, that means you have about 50lbs to lose. if you're 6' tall, that means that you're starting out at a healthy weight and trying to get down to what's basically underweight and 1/4lb per week would be a pretty reasonable loss per week. if you're 5'6" that means you're starting over and ending up in the bottom third of your weight range, which isn't that far off. a reasonable loss per week is going to be about half a pound per week, though you might be able to see 3/4 or a full pound a week for the first ten or fifteen pounds. if you're 5' tall, then you could reasonably expect to be losing a pound a week with perhaps a 1.5 or 2lbs here and there for the first twenty pounds.
so if you are 6' tall, losing those 14lbs in the past year is right on par with where you should be. if you're 5'6" tall, losing 14lbs in 4-6 months is great progress. if you're 5' tall, then losing 14lbs in the past two or three months is great. losing 50lbs isn't a five or six week process, at least not if you want to lose it and keep it off. the taller you are, the more likely that you're already at a healthy weight and the slower the weight is going to come off. the shorter you are the more weight you have to lose, so it's going to go a little quicker. but time frames like "quite a while" coupled with "little success" are a bit vague. 14lbs is decent progress.
-google first. ask questions later.