Hi Bec!
Remember me from baby buddies?!
Can't offer any advice at all, but just letting you know that we are going through exactly the same thing here with our 7 month old DS - waking every 25 minutes at the start of the night, and then if we are lucky we get a 3 hour sleep at around midnight before the boobfest begins again. Am joining you in tiredness Its so hard to get a baby to sleep during the day when you have a toddler running around too, do you find that? Our DS is too distracted by things to feed during the day, and I can't lock myself away in a darkened room to encourage day feeds because Milla will barge in and want to chat, poor girl. So yeah, he feeds all night and is awake most of the day too.
Good luck, and take care of yourself. I know how hard it is