Help with twin's schedule

My twins are about to be 2 months old and they're eating every 3 hours. I have them on a pretty solid schedule so every three hours at least one baby wakes up on their own ready to eat. To keep them on the same schedule I wake up the other to feed.

I mostly formula feed since I'm not producing enough milk and I'm curious if anyone has any advice on getting them to go longer in between feedings. I read that they should be eating 5 times a day but my babies are still eating 7-8 times a day (sometimes i get a 6 hour stretch at night).