How can I hammer this deal

hello all
I have a house that is FSBO. currently I have an offer on the table from somone that is kind a low and I am looking for best possible one. Another individual liked the house, approched and made an offer that is higher. But, the second individual has an agent and I agreed to pay her 2.5 %. after I factor in her commision that offer become lowest offer. Remembering that the individual liked the house and wants to have it, I am willing to comprimise a little my numbers to reach the deal. the buyer is willing to go up a little. the question is how can I work out a deal with the agent and try to convince her to take a less to reach a deal ( less than a half). no ther agent is involve. she can make or kill the deal
all your inputs is greatly appreciated