How many times does a toddler "need" to feed?

My little one is almost 17 month and I've been exclusivly breastfeeding since birth. He now only feeds twice a day : morning as pre-breakfast and evening before bed.

His evening feeds have been hard lately, he is way more interested in books, playing, his dad, the dog, really anything else than my boob. However once he latches on enough and I can feel the letdown start he relaxes and feeds on both side but it can take a few good try and me almost forcing him to stay put.
The morning feeds are very calm and relax, no fussing or issue whatsoever. He even cries if I'm the one that takes him out of bed and don't feed him directly.

My question are,
- how much milk does a 17 month old actually needs? (as in nutrition)
- how would you go in weaning him of the evening ones?

For now all his other feeds were really stoped by my observation of his needs and wants. If he wasn't fuss anymore for a few days in a row I stopped offering and he was completly fine stopping. I'm a bit torn on the night one as even though he fusses about it at the start once the milk comes he happily eats on both side.