I use the TDEE calculator below to figure out how many calories I need per day. This gave me the most accurate number (it was very close to the number I got from my dietitian too).
I've found that the best app/website (for me) for calorie counting is My Fitness Pal. But you have to input things in very specifically to get an accurate count. However, I only use it for tracking calories and I don't follow their "recommended daily calories" amount as it's usually lower than I need.
You'll find that weight loss is mostly affected by what you eat. You can't out-train a bad diet. But exercise will definitely help you feel and move better!