Pep talk time! (I'm going to type what I've told myself so many times in the last three months since above sounds like the other side of the conversation I've had with myself at those times)
Bob, don't give up yet! I've just managed to get my 5.5" f5.6 to better than 1/10 wave. Even though this is my first mirror, I've put enough time into figuring that I feel like I'm an expert. The biggest lesson I have learned is to go slow. Try a session or two with only 5-10 minutes of figuring strokes with only the weight of the mirror on top. Keep your fingers on the sides, no pushing on top. I am still amazed at how fast this changes the figure. Only plan on one session a night, take your time and I'm sure you can get there.
You really want some correction in there to be able to see fine details for planetary work. And be honest with yourself, do you really think you will ever go back and work on this mirror if you stop now? After all, it won't be any easier later than it will be now. It sounds like you have a well working lap right now. If need be take a little break and work on the rest of the scope and throw a figuring session in every now and then. But just go slow and sneak up on the perfect figure. Don't let your past overshooting worry you. You are much more experienced and talented now then you were way back then. You're almost there, I know you can do it.
Tony the Energizer