J.K.
Hi, my son is almost 5 months old now adn I ran into a very similar situation about a month and a half ago (so did my friend with a baby the same age!). We just felt like we weren't producing milk (boobs not getting hard- not getting as much when/if we pump, etc)... Chances are you HAVE enough milk- it is very rare that a woman can't totally take care of her baby. It is normal for your breasts to "figure it out" and not have to get hard anymore- they know how much the baby needs based on how much he/she eats.
Also the age of your daughter is when they start being very aware- which could be why you say she is fussy. My little one didn't want me talking during feedings (to distracting), would turn his head (with my nipple still in his mouth- ouch) when there was a noise in the room, started playing with my hair/ necklace/ clothes while eating, and refused to let me put something over his head (while nursing in semi-public places). She could also behaving a growth spurt and her needs temporarily have increased- your body will adjust in the matter of 2-3 days if that is the case.
They totally get beyond this. As long as the baby is wetting 5-6 diapers a day and having (somewhat) regular poopie diapers she is getting enough. Your 4 month apt is coming up- you'll be able to see if she is gaining weight normally. Moms and husbands are tough- whenver the baby makes a peep- she's hungry. I went through what you are- and my baby still hasn't had rice cereal- or anything other that breastmilk and he is 20 lbs at 5 months and F-I-N-E! My breasts never (very rarely) engorge anymore...Relax, your body will take care of your baby.