Well, I'm on my third baby currently, &, so far, he's sleeping/eating exactly the same way his older sister & brother did.
He sleeps about 2 hours at a time & wakes up to nurse/suck. Yes, he uses me as a pacifier. I know this. No, I cannot let him CIO. I couldn't let my other 2 CIO it either.
All 3 of my kids have needed to eat every 2-3 around the clock until they were around 10 - 12 months old. I nursed exclusively w/ older DD & DS & introduced rice cereal at 4 months & baby food at 6 months w/ continued nursing. We nursed for a year & started weaning at 12-14 months.
W/ our current baby, I nursed exclusively until 5 months - we're working on rice & oatmeal cereals now & plan to introduce baby foods next week when he turns 6 month & will continue to nurse until he's a year.
When all 3 were first born, they needed to nurse every hour to every hour & a half. I currently haven't had more than 2 hours of sleep at time since July 16, 2009. Yes, I'm tired. And, no, I don't have "the time just to lay around in bed all day & night nursing". But I also wouldn't trade this time w/ my baby for anything!
But this too will pass. We co-sleep to make the night-time nursings easier & he has a pack-n-play right beside our bed. I so enjoy holding him & cuddling him. Honestly, that first year goes by so quickly! I think having this third baby so many years after my 1st 2 (DD is 10, & DS is 8 - they're 18 months apart) has made me realize how fast the time goes... DH & I are enjoying this baby so much!
My older DD & DS have no problems sleeping now. They both sleep in their beds all night long & have done this for many years now. I never let them CIO & by 18 months, they were both sleeping in their own beds all night long.
And, honestly, it's not helpful AT ALL when people suggest just giving the baby formula/cereal to "help him sleep" or to just let him CIO. Breastfeeding is an easy-hard thing - the process, once the baby & mom get the hang of it is easy, but the frequent feedings can be exhausting. When my DD was a baby, my mother often suggested that I just give her some formula to help her sleep. Not what I needed! What I needed was encouragement. And support.
There is nothing wrong w/ a 4 month old baby needing to frequently nurse. While some BF babies may go longer between feedings many BF babies do not. I think lots of new moms try breastfeeding & give it up because they're not prepared for the "around-the-clockness" of it & then don't get the support they need.
And there's nothing w/ wrong not letting a 4-month old CIO. A 4-month old is a little baby... I just could never let my baby cry himself or herself to sleep. And, like I said, my DD & DS sleep fine now.
So, to the OP,

. I know you're tired. But she'll get over this little spurt & will settle back down into some longer sleeping patterns soon. My baby was sleeping from around 11:00 pm until about 2:00 am, waking up for a quick nursing, & then going back to sleep until about 5:30 am before Christmas. Then, the week after Christmas, he got in this pattern of only sleeping for about 45 minutes at a time - he did this for about 5 nights. I was exhausted!! I decided that maybe I had been eating too many sweets & drinking too much caffeine over the holidays, so I started cutting back. He's slowly getting back to a more workable sleep routine.
We've been feeding him rice & oatmeal cereal (started at 5 1/2 months), but that really hasn't increased his sleeping very much. He's a catnapper.
Try to get your DH to help more! My DH is very supportive & helpful - I'm not sure what we'd do w/o him! The week that DS wasn't sleeping, DH would take him in the mornings, & I would sleep for about 2 hours. (DH works swing shifts, & DS's "no sleep" days happened to coincide w/ DH's off days.) DH will also take him, so I can escape to the shower for a while.