Chantel I think you can gather from the other posts that you are DEFINITELY NOT a bad mom - I think it is just a stage they are going through where they want to do things there way and dont have any other way to express it.
I think the best thing to do is just to TRY and stay calm - and if you are feeling like you are losing it then just leave her in her cot where it is safe and take a time out

I have done that since my LG was a newborn - it was safer for her to be in the cot crying than with me when I was getting more and more frustrated as I didnt know what she wanted and it hasnt changed much in 18 months.
Just think about how you feel when you want something and cant get it or tell someone about it - I do that and it helps me sometimes realise that she is a little person with frustrations too!
As much as we want to give them everything they want they also have to learn boundaries and that they need to fit in to what mommy wants.
EASIER SAID THAN DONE I KNOW