congrats
it IS really difficult. if you think hes having problems with constipation you might want to try letting him soak in a baby tub (you can get a little sling time thing that goes on/in the baby tub so just his little booty would be in the water) and run water over him, under his stump (with a cup or something) then when you take him out put a bunch of patroleum jelly/a d ointment and (i know its GROSS but it helps) put a little bit in his booty, it really helps, val use to have horrible problems with constipation and it helped SO much
also dont be too conserned about the weight, val was born at 8 lbs 10 oz and when we left the hospital she was down to 8 lbs and it was fine (a few days later she was down to 7 lbs and then they started to worry, but thats not the point)
i cant really help you on the breast feeding, it didnt work for me, have you tried cutting things out of your diet that could be causing problems?