Allow me to repeat what everyone else has told you: 11 pounds in 4 weeks is awesome! That's close to three pounds a week. You can't compare to what others have lost, because every body is different. Some bodies lose more quickly, others shed slowly. Some people are older, younger, heavier, lighter, taller, shorter...you get the picture.
Anecdotally, I can say that yes, insufficient calories can provoke a stall. I stalled out for a month and broke the stall by continuing to eat moderately (I'm a calorie-counter), but ceasing my counting/measuring/weighing of food for a week. I don't know what my caloric intake was--that was the point, after all
-- but I'm sure it was higher than the 1500 I've eaten for months. I stalled at 193 and, well, you can see my ticker: now I'm 189 after a couple of weeks or so of going back to counting.
I wouldn't count anything less than a month of standing still as a plateau, though; a lot of people get upset if they don't lose weight two days in a row, but weight loss isn't that linear.
Relax, you're doing great.