Iphone 4s won't back up because not enough storage after deselected and deleted all messages.

I read and followed the step from Apple website. Also went and deleted all my message which is about 1.9gb. I also un selected all the option from the backup menu. How come i still couldn't back up my phone. iCloud keep giving back error messages. Also time to time all the contacts diappeared for couple of hours then just reappeared out of no where. Please help.