oh mate, sorry, but it's really normal at this age. Hopefully it will be a short-lived phase.
It's also possible she's reacting to something - illness, teething, separation anxiety...? Although she's feeding each time, it's quite likely there's an element of comfort feeding in there also. If it's you she really needs right now, then solids might not help you anyway.
Is there anyone who can come and help you out during the day, at least with your boy? Do you bring her to bed with you? That's the only way I've managed to get any sleep and I also hand over to DH for a few hours when she's been particularly bad. DD also stretched her sleeps out overnight for a wihle, then aournd 3-4 months, it was all over. Since then, with a few nights exception here and there, she's fed every 1-2 hours most nights. yay. For us it's been a developmental thing, but also due to prolonged illness over winter (over now, knock on wood) and teething.