Eating less than BMR?

I am female, 5'3 and 115 pounds. I calculated my BMR and it is a little less than 1400 calories a day. Using a calorie counter, I have been tracking my calorie consumption and have found that I usually eat about 1000-1200 calories a day. For example, for breakfast, I might have an apple and a glass of soymilk, which adds up to 200 calories at the most. Then for lunch I might eat a salad with artisan lettuce, tomatos, cucumbers, and cottage cheese, and a slice of whole wheat bread with Nutella, adding up to less than 300 calories. For dinner, I might have a slice of pizza, dumplings, basically anything that my mom cooks, which is usually around 300 calories. Throughout the day, I drink plenty of water (no juice), have snacks like nuts and fruit, and maybe even a cookie, adding another 200-400 calories. I'm pretty sure portion sizes are calculated correctly. I feel full and have plenty of energy, but many websites say that eating below BMR is unhealthy and makes you tired. Is it ok to eat below my BMR?