Great to see you keeping up such an active lifestyle! You don't mention your height, but anyone weighing 155 pounds, with lots of muscle, and daily 700 calorie workouts, surely burns much more than 1500 calories per day.
The most likely explanation is that you are eating more than you think you are! I would try measuring my food servings just a few times so you have a better idea of what "3 ounces of chicken" looks like or "1 cup of pasta". You may find out you are overestimating some serving sizes by 50%, which is common.
Another common way people underestimate their intake is by letting some snack foods slip under the radar. You may well remember having a healthy breakfast, lunch, and dinner, but what about the coffee drink you had when you met your friend late morning, or the ice cream cone you picked up when you took your son and his friends out after school? At the end of the day, we tend to forget the foods that we would like to forget we ate! The fix for this is a food diary; try keeping one for a week or two, writing down everything you eat within 20 minutes of eating it. The diary doesn't have to be anything fancier than a scrap of notebook paper tucked in your pocket or purse--it's just a way to track exactly what you are eating.
You may find a couple of hundred extra calories hiding out between meals and on serving portions that will be the answer you've been looking for.