Nap time help!!

[gibbylod]

Please please help! I am at my wits end!

DD1 refuses to nap. She is only 21 months so I think it's still way too early to be done with naps, right? If she doesn't nap, she is absolutely impossible for the rest of the day and by dinner time she's so exhausted she won't eat. I've tried reading to her, rocking her to sleep, giving her a bottle before her nap, moving nap time earlier, moving it later. She just screams and cries until I finally give up after an hour has passed and I'm in tears too! The only thing that works is putting her in the car and going around the block. And there are some days that doesn't even work.   

What am I doing wrong?! I don't know what else to do. Please help!