Even when you feel empty, there is milk so baby will be getting some although the flow will be less. It's especially important to let s/he feed on demand during a growth spurt as this is what cues your milk production to increase. Just make sure baby is latching on properly (so you don't get sore) and hang in there - your supply will increase, it just takes a few days. When my DS was 4 months old, he went on a super growth spurt and it took a while for me to catch up. He even needed a feed in the middle of the night for about a week which was really hard as he'd been sleeping through for a couple of months. It did settle down though and I'm sure it will for you. Good luck!
Definitely feels like this but if you squeeze in the right place there will always be a dribble left I've had lots of success with fenugreek - £10 for 100 tablets from Holland and Barrett (probably cheaper elsewhere), and take a whole load (4 tablets 3 times a day ish). Also oats, if you like porridge!