Is she bottle or BF?
Thinking if she is BF maybe its more using you as a pacifier than eatting?

But now that she is 4 months you can start her on Cereal. Thats what my kids doctors said. That might fill her up alittle.

Not much try alittle tsp. or so and give it a couple days to make sure she doesnt' have an reaction, then you can increase it, try that for about 2 weeks or so then you can introduce alittle solids. you can mix the ceral in the solids to give favor.
Prunes, pears work great if she starts to get constipated.
But its something to talk to your doctor about at the 4 months check up.

the cereal is a good idea. if you arent comfortable doing that yet i would just increase her formula or breastfeed her more if youre doing that. chloe would go through stages of being hungry all the time, thats when i know to increase her food amount

She is bottle fed.I will start her on cereal to see how that works.I think she is teething too and she gets so uncomfortable that sucking on her bottle makes her feel better..

most babies usually go through a growth spurt at 4 months. if she is able to hold her head up and sit up with assistance or in a highchair, then i would suggest trying rice cereal to start.

if you think she is teething and is really fussing, try putting a little dab of baby oragel on her gums to see if that helps. if you are not comfortable using baby oragel, and use pacifiers, i would suggest putting the ones shes not using at the time in the freezer. i do this with my son and so when i notice him really fussing and chewing on something hard is not helping i will give him a cold paci. i also put his teethers in the freezer too. it seems to help.