What am I worth?

question? i am a new anp and have been at my place of employment for 1 year now. i am getting ready to renegotiate my contract and am wondering what is fair to ask for in regards to pay. when i joined the practice i was just getting started as an anp and accepted the position getting paid what i was paid as a staff rn. i am having a difficult time because my skills are not "expert" but i know i should be making more than i was as an rn. i work in surgery so i primarily assist in or cases and see post op patients in the office and hospital (so these are covered under the "global" cost of the surgery). i am working in a suburb outside of chicago, il. any advice would be greatly appreciated!