Help me choose my marathon plan!

Hey there Mommies! When I signed up for the Newport Marathon, I had exactly 18 weeks, which is a typical training cycle. Usually, I decide my plan right away and stick to it. This time, I found 3 different plans and was trying to decide between them. 2 weeks into it, I decided not to do speedwork, but just focus on getting in slow miles to build my base. Here is what I have run each week:

January- In the whole month I only ran 10 miles! I had been running 15-20 miles a week before that for about a year.

January 30th-February 4th- 22 miles, including an 8 miler and 9 400 repeats!
February 6th- February 11th- 25.9 miles, including a short pace run and a 10.5 mile long run
February 13th- February 18th- 25.2 miles, including 2 800m repeats and an 11.2 miler.
February 20th- February 25th- 10 miles, took some heavy medication and was wiped for the week.
February 27th- March 3rd- 35.9 miles including a 13.1 mile run- no speedwork, all low heart rate.
March 5th- March 10th- 35 miles including a 12 mile run

So, that is my first 6 weeks. I have 12 weeks until my marathon. I am kind of antsy to start speedwork, but wondering if I should still just focus on slow, consistent mileage. I have friends who have used a pretty intense 12 week program that I am considering and it has 2 days of speedwork. I have also looked at the Hal Higdon schedules which I have used in the past, and the "Finish It" schedule from Sarah Bowen Shea and Dimity McDowell's new book Train Like a Mother. I am just having a hard time figuring out my goal for this marathon.

I would love any advice from all of you!!! What plans have you used? What are you using right now? How do you decide your goals?

I know I overthink everything, but I am a numbers girl!!

My marathon history is:

1st marathon- June 2005- 5:11
2nd Marathon- May 2006- 4:36
3rd Marathon- June 2006- 4:45 (got lost and actually ran 27.2 miles!)
4th Marathon- October 2007- (5 months after having a baby!)- 4:06
5th Marathon- April 2008-4:03
6th Marathon- May 2008-3:48 (Current PR!)
7th Marathon- May 2009- 4:14
8th Marathon- October 2010- 4:18

I was in the best shape for my 2008 and 2010 marathons. I have about 15 lbs to lose to get back to that shape. :-) So, I am trying to decide a realistic goal. My ultimate goal is still a 3:40, but there is probably not enough training time this go around.

Thanks for your help!!