A few pregnancy questions i didn't ask my dr? HELP!!!?

I had a few questions i forgot to ask my OBYN & i don't feel like waiting till next month to ask her so i'm hoping you guys can please help & just give me your best answer from what you know. I found out i was pregnant when i was 5 months i'm very petite i weight 96 and i'm 5'4 now i am 7 months & i weight 108.2 so far i've gained 12 pounds don't know if that is good. Everytime i go in for a check up she says everything is good & that the baby is growing how its suppose too and it has a strong heart beat is that good. Why does the dr always makes me do urine samples? She said i've gained 12 pounds so far & i need to gain at least 8 more what if i don't?? How can she tell the baby is growing right by measuring my belly? She doest always gives me ultrasounds cuz its bussy would it be rude to ask for one? if i ask my dr would she be able to tell me how much the baby weights so far or can i find out from an ultrasound? Sometimes my urine is clear like water i know its because i drink water if i don't drink water all the time during pregnancy is it bad? I move around the house alot do chores bend down do alot of walking can that affect my pregnancy? my last question is sometimes there is no food in the house so i dont eat or just eat a bowl of cereal the whole day or toast is that bad?