Quoting jo-jo:" Hi, I have not been in the same situation but my younger sister has, she got pregnant three months after ... [snip!] ... even though she was tired . She swears that the routine she created and stuck to for her and the kids is what kept her sane."
routines really help and so does being organzied...i am slacking in the organized department right now, but i know when i get further along and nesting instincts kick in, it will all come back..
OP.. its not that bad. i have a 4 year old, 2 year old, and 1 year old and I babysit a 4-5month old during the week. Its tough. but do able. i can still get on BG, and when both babies nap i can clean up and stuff.. sometimes even sneak in a little nap with the big girls and we all sleep. good luck! its not too bad, it takes a couple months for life to start to feel "normaL" again after having a new baby