Snacking is fine, especially when you are BF. The issue is choosing the right things to snack on. Healthy foods. Grab some sunflower seeds instead of chocolate or an apple instead of cupcake. Just things like that. Also avoid sugary foods and drinks at all costs. With a little adjustment to the foods you are snacking on, you shouldn't have a problem. You really NEED to keep up your energy and intake when you are feeding.
Oh and another thing is if you think you are hungry, have a large glass of water and wait 10 minutes. Sometimes we think we are hungry when we are really just thirsty
Good luck hun! Sounds like you are doing a great job with the exercise!