Stopping breastfeeding

[Namechangeymcnamechange11]

DS feeds to sleep at present. He's nearly 14 months.
He's clamping down and pulling off at the end of a feed, or just whenever he feels like it to be honest. Then laughs about it. He's too young to understand no. This is also going hand in hand with fighting sleep.
He only breastfeeds at night and to sleep at the moment.
Help! My poorly nipples

Ouch! Have you tried taking him off the nipple when he does this? I noticed my daughter used to chomp on me when she was getting tired or distracted so I tried my best to keep her engaged. I also found that when she did clamp down on my nipple if I pushed her into my boob slightly she would have to unlatch in order to breath. Could be worth a try?