I want money soon but im missing one w2...?

i made 31k last year. the w2 i do have says 23k and the other im missing says 8k. i claim 2 kids and file jointly with my wife who doesnt work. if i file an amended return today with my 23k w2 will i get back alot less than im suppose to? or will i get back more and owe the government? i will not get my 8k w2 until the 23rd and thats too long to wait for what i need to get so doing it this way will i lose money and wait longer to get the rest? or will i gain money and have to pay it back? or will it be the same refund? (0 fed. withhold all year)