M.L.
You can make up for it on the weekends! Charge your camera battery, and take tons of pics of your baby for his 1st bday. Create one family night a week. That is the night where you focus really hard on having a fun game night, a lesson, sing a song. When they are going to their rooms, spend 10 minutes every night with each child to say a prayer and read a story. I know you are tired and it's their bedtime, but you all need that special time, even if it's just a short period of time. If they go to bed an hour later b/c it's being spent with the family, then that's just fine.
One thing we do that can work for you... is we have a late family night with one child a week. Every Wednesday, one child stays up late with mommy and daddy while all the other kids go to bed, we have a late night snack, watch a short movie or cartoon, play games, back rubs, sing songs, cuddle... Then the next week. it's another child's turn.
Create times when one child goes out with you. I take turns with mommy dates. On nights I go grocery shopping, one child comes with me, we go for ice cream, then we go shopping, while the other kid is home having bonding time with daddy. The next week, it's another child's turn.
On Sunday's, it's family day... no exceptions. No birthday parties, no going out, no homework, no work, no meetings, no grocery shopping, no tv, no internet... it's our day where we recover from the week and spend time as a family.
Also, learn to say "no" to unimportant things. I love this speech... maybe it will help you:
http://new.lds.org/general-conference/2010/10/of-things-t...
(when he brings up the airplane... it's because he's a retired pilot and always talks about planes).