9mo won't drink enough milk

DS is 9 months and I don't think he drinks enough milk. We are mix feeding - he breastfeeds morning and afternoon, then formula (soy) at bedtime and if needed overnight. A couple of months ago he was sleeping through the night. At the time he was on 4 BF and 1 formula overnight if needed, as well as 3 meals.

Now, he is eating 3 big meals per day, has a good breastfeed in the morning, a halfhearted one in the arvo and I'm lucky to get him to have 100ml of formula at bedtime - then he wakes for a feed anywhere between 10 and 12pm. We switched to formula at bedtime cos I was tired of fighting with him to get him to feed, trying to force my nipple into his mouth :(

So I think he isn't drinking enough milk before bed but I'm not sure how to get him to drink more so that he will sleep longer. He has dinner at about 515-5.30 and will then snack on some sort of finger food until we have finished eating at about 6. Then bath and short play and I usually start his bottle at about 6.45 before bed at around 7.

Does anyone have any suggestions?

Maybe he's ready to drop the half hearted one in the afternoon? When DS1 was ready to drop a feed, he'd show little interest in it and wouldn't drink much, that's how I'd know.

From memory around the 9-10 month mark some babies often reduce a feed or so, they just don't need it. Sounds like your LO is still feeding well otherwise.

How is he? Growing, healthy, etc?
Sounds like he's eating a lot of food, so not really surprising he'd be having less milk. If you think he's suffering for it, you could cut back on the food.
Your concern seems to be more that he's not sleeping like he used to be? It's pretty normal for these things to change and it often doesn't matter how much milk they take during the day, they just wake up anyway.