You are both very yound and your b/f just hasn't grasped all that is involved with children around. He seems to be a bit selfish which is understandable at his age ( I am assuming that he is close to your age). You need to have a mature discussion with him and let him know that it's not him (a lot of guys take things personally when it comes to sex) and with all the responsibility you are just tired many times. When you talk stay away from accussing each other, instead use the phrase, when you do X it makes me feel like Y.. Come to some agreements about couples nights and frequency of sex. Good luck..
boyfriend has to mature. you're adults with responsibilities, schedules, endless to-do lists, not jackrabbits. no way was i even interested in sex even when my baby was 6 mths. i was always too tired and stressed. perhaps he should be willing to sit down and discuss as adults you two planning a couple of "couple nights/date nights" where you put the kids to bed and then you'll have time to spend and dedicate with each other. but once a day?! whatever! he should have thought of a vasectomy before you guys welcomed child number 3 into the household. im surprised it's even possible
I completely agree with the above post - this is perfectly normal! My baby is almost 11 months old and my sex drive is still working at getting back to what it was pre-baby. A new child strains a relationship and you as a mother, and you need to not only cut your self some slack, but so should your boyfriend. You will need to find time for yourself - and as stated, sometimes the chores are just something that can't happen that day and that is okay! My mother always said she wishes she had let the house be dirty for awhile so she could've enjoyed playing with us kids more and her life as well - remember that :) Good luck!
The fact that you feel under pressure to have sex when you are not feeling like it is a real passion-killer in itself, and really damaging your chances of doing it because you actually want to at some point. Pressure is not conducive to good sex.
Also, you've only just had a baby! I guess it is different for everyone, but I know I didn't have sex at all with my wife for a few months after the birth of each of our children, and for several months after that it was infrequent. Initially she didn't feel fully healed and comfortable after the birth, but even after that her desire was low, caused by the strain of looking after a baby, and the sleeplessness, and the stress, and feeling like her post-pregnancy body was unattractive - all of these will lower the libido. This is quite normal, and there's nothing wrong with asking him to cool it a bit until you are more in the mood.
You're quite young, and I'm guessing your boyfriend is too - at that age I was certainly up for daily sex, and I can quite understand if that's what your boyfriend wants - your situation won't have affected his libido they way it has yours. But if he cares for you and respects you, he should be capable of backing off for a bit when you need him to.
You mention that even when you don't have sex all he wants to do is sit and do things together. Generally this is a good sign in a relationship - he wants to spend time with you and share experiences! Quite likely he's feeling left out - with all the attention you are paying to your baby (and your other two kids), and the time you spend doing your other chores, there's no room left for him. He's feeling left out of your life, and not receiving the attention you paid him when you first met. If you don't get to spend a bit of time together, even just chilling and watching a TV program you both enjoy and chatting about it afterwards, or discussing future plans together, your relationship is likely to suffer. Sometimes the chores just have to be ignored for a while.