Your current mileage should be more than enough to get you to your marathon goal and more. The only thing I might mention is to make sure your easy runs are easy. I have seen a lot of miles in the 7:xx range, which was one of the mistakes I made earlier this year. I ended up wearing myself out a bit and got injured (although not severely). I have had to sometimes work hard (and have not always been successful) at keeping my slow miles below 8:00/mile just to make sure they are easy. From a speed work perspective, my own goal has been to not introduce any speed work into my running until I hit 50 mpw. You are already there, go ahead and put in some tempo miles, MP miles, striders, etc., but not too much, maybe just once a week to start out with and probably no more than 2X per week. You will want to make sure you are getting in some quality long runs at an easy pace to get your body used to running for a long period of time. Don't worry so much about the distance, more about the time. Your 5K and 10K, as well as the 1/2 marathon, should also give you a good idea of what to expect to be able to do for the marathon. My personal rule of thumb has been that my 5K pace is basically about 1 minute/mile faster than my marathon pace (at my current level of fitness). Obviously this formula does not work for the elite runners on the blog, but it may help you to get a good idea of what you are capable of. I would also recommend starting to introduce some MP miles into your long runs, maybe start with 3-4 (after a couple miles warmup), and work your way up from there until you are up to 10-12 MP miles on your long run. I can already tell you that you are much better prepared for your upcoming marathon than I was for my first, or even my marathon last year. I have found that by far the most important thing is to get in the aerobic training, which you are already doing. Keep up the good work, you will be prepared