Day 18 and I am doomed...suggestions?

I am on Day 18 and can't seem to get my humidity higher than 60%. I have a brower top hatch incubator, have filled all the water wells as high as they will go, added 4 soaked sponges (can't fit anything else in the incubator) and even added a humidifier to the room the incubator is in running it on high and shutting the door. The humidity is holding steady at 60% for the last 8 hours . Any suggestions as I don't know what else I can do at this point Am I doomed to have the chicks sticking to the eggs and not hatching? I live in South Dakota, where it is very dry during this time of the year, humidity in the house is 20%(the humidifier in the room with the incubator has raised the room humidity to 30%, but no higher)
Z

 

Thanks for the tips. I also got a tip from crazychicken in the chat room about putting a cup filled with water and the sponge sitcking out of the cup (only thought about putting in a soaked sponge ). That, and giving my humidifier a full 24 hours instead of 8, and humidity went up to 65%. But from other posts, I have seen it is best not to raise the humidity until the last two days as opposed to day eighteen, so I am backing off to 50% until tomorrow (Day 20). I thought about putting eggs into an egg carton (from Zunibee's blog) as opposed to letting them sit on the wire mest on the bottom of the incubator. Anyone else try hatching this way?

Thanks!

Z