Frustrated and floundering a bit.

I've been at this for about five months now, with no small degree of results yielded, but I still feel I want to go a bit further (original goal was 180, but upon review I want to -try- for 160.) I'm currently at about 15-16% body fat, which is certainly better than what must have been high twenties or low thirties when I started, but what's left is largely around my gut; I like the way my chest and arms look by and large, but I swear looking at my stomach I still feel as fat as I ever was in some ways.

For the past three weeks or so, I've hovered consistently in the mid 170s. I'm getting a little discouraged, because at first, I'd actually lowered my calorie goal as low as 1600 for those three weeks (I've just today, in efforts to change -something-, bumped it up to 1800, which I'm sure is still probably a bit low for a 6'0" male at 175 lbs with my activity level.)

I've also been switching up my cardio regimin quite a bit recently...I got tired, tired, TIRED of doing the elliptical at the gym (~8MPH for 30 minutes 5x weekly.) so I moved to a 4.5 mile hour long walk, which has just this week graduated into a 45 minute 4.5 run/walk, and also trying to throw 7-10 mile bike rides in here and there. My weight lifting has been a steady, three to four days a week alternation between 21 sets of arm/leg strength training, and 21 sets of chest/back (rows, deadlifts, chest press, etc) with a hundred crunches each day.

I feel like I'm at a pleateau, and it's frustrating given I'm clocking in at about 1000 below TDEE. Yes, I had a lousy day monday (low-calorie mayo deviled eggs were the culprit there.) and a TERRIBLE day tuesday (pizza, and popcorn at the movies.) but (and you'll have to take my word for this.) My cheat days are usually 10 days apart, and usually amount to little more than 1000 over my 1800 goal.

I feel frustrated just because I had -big- losses in April, and they came screeching to a halt this month. I'd really, -really- like to see how I look even just ten pounds lighter, but I'm starting to lose steam. Often when people say they've hit a plateau, people chime in saying that they must be eating more than they think and logging inaccurately. 99% of what I eat is packaged, portioned foods (Hard-boiled eggs, granola bars, small frozen pizzas, low-calorie jell-o puddings, sardines.) so I'm -fairly- confident in their accuracy. Even at a 20% margin of error, I ought to be losing. The only thing I'm consistently eating that isn't individual portions and that I don't weigh/measure is a bit of ketchup on my hot dogs, and I call it fifty calories, I can't imagine at the worst case it's even double that.

Do stalls really happen "just because" and the whole non-linearity thing is true, and I'm not just at a pleateau for lack of eating better/working out more?