You should definitely not feel stupid. The LSAT has made all of us feel stupid at one time or another, and trust me, given the collective intelligence of this group, I would say the problem lies not with us but with the LSAT!!
It's like beating a dead horse to say it again, but yes, postpone until October. I would never, ever take the LSAT with a week's prep. Take a Princeton Review prep class - I strongly believe they are the best company at really teaching HOW to take standardized tests - and plan on October.
Even though you don't need a strong LSAT score for the school you want to attend, you will wonder if you could have done better, and you will stress about how you'll do on the bar. There are bar exam prep classes too, and you'll have four years of law school to help prepare you, so go for it, do your best, and you will succeed. More power to you for following your dream and having the courage to change your life at 40! That is very cool.