why don't my kids listen to me?

i mean seriously, why don't they? i try to be a good mom. i always thought i'd be the kind of mom that i wanted when i was a kid. am i? i don't know. all i know is i open my mouth and apparently nothing comes out.
my youngest is 2 years old. he is a holy terror. he is a sweet, affectionate, caring, loving little guy...when he feels like it. the rest of the time he is stubborn and ornery! he is sneaky and will not listen! i am currently searching for products to remove the black sharpie off my loveseat...yeah, that's fun...
he had a 45 minute fit a couple days ago...45 minutes of screaming! i mean, i try everything, but he is just never satisfied. he is going to send me to the nuthouse...can you tell i'm frustrated?
i don't know what he needs, but it's obviously something i'm not doing. i swear i'm going to call Super Nanny! maybe i just got spoiled with my oldest who is almost 5. He never ever did the things my 2yo does. i know you're not supposed to compare your children, but i was so spoiled. J has always been a joy. not perfect, not without his own trials for me, but a Joy!
G however, has been a trial since the beginning. I love him as much as any mother could love her baby, that's not the issue. If that weren't true he would probably be hanging, wrapped in a duct tape cocoon in his room by now. it just never stops with him.
the thing i worry most about is him being happy. i want him to be fulfilled and expressive and joyful. not always in trouble. not always having mommy and daddy telling him, "NO!" i want him to have the best, be the best. but i feel like if i can't get the basics through his skull he'll never have that.
SIGH.....
i love my kids...motherhood is hard....this is no newsflash...
i just have to keep praying and trying, never give up, never give up...
i mean is that even an option?