I don't know what your age is, and age is a factor in how many calories you eat. Have you tried using one of the online calorie calculators to figure out an estimate of how many calories you should be eating? I like this one:
http://www.freedieting.com/tools/calorie_calculator.htm
Just for curiosity, I put in the stats you presented in your post---i.e., 170 lbs., 5 ft. 5, and exercising 5 days a week (although in my own case, I always prefer being conservative with figuring exercise, so I choose the lower option). I arbitrarily put in age 35 for you. It indicates that you need 2148 to maintain the weight of 170. To lose a pound a week, you would have to subtract 500 from that number (so, 1648 calories per day). This is just an estimate, though, and your actual calorie needs may be lower than that. And, again, it depends on your age.
So, the upshot is that 1800
may be too high for you to lose weight in a way that you would notice. Also, perhaps you're losing, but at a very slow rate (1/4 lb. per week) and if you don't have a digital scale, you may not see that loss.
Also, are you weighing and measuring your food? If you estimate calories, you can often be off by hundreds of calories a day and that will definitely stall your weight loss.
I've found that exercise helps with fitness, toning, and muscle mass---all very important. But IMHO, its effect on weight loss is overrated. I used to think if I exercised, that that gave me license to eat more, but it doesn't. Somehow it just doesn't work out that way. (There are studies and theories as to why, which I won't get into here).
I know it's discouraging to think about eating fewer calories than you're currently eating. Believe me, when I put in my stats for how many calories I will be able to eat when I reach my maintenance level, it turns out that I will only be able to eat 1600 - 1700 calories TO MAINTAIN. That sucks, and I threw an inner tantrum ("That's not fair!!") when I first realized it. But it is what it is, and I'm trying to learn to deal with it. (It's either that or stay at my current weight, which I don't want to do).