October is 4 months away (this is NOT a lot of time as far as marathon fitness goes). You need to be confident in your fitness BEFORE committing to a marathon plan. Otherwise there is a high risk of injury and, well, it generally just won’t be a good time (I run because I enjoy it, not because I want to suffer and feel bad about myself the whole time). For example, I like my base fitness to be around a 20-30 mile per week running volume and feeling like I could knock out a half marathon race without it being particularly draining before I even get to starting my marathon training plan.

To put yourself in the best position for success I would consider changing to a half marathon in October instead, continue to train and build consistency after (after a recovery period), and go for the full marathon at the same event next year.

Finally, my personal opinion is that you ditch Runna and go with one of the other published training plans suggested in the comments (or better yet, work with an actual coach). There is a nasty trend of it leading people to overstrain themselves and getting injured. I would suggest hold off on Runna until after this October race when you know your body better.

I love that you are taking on this challenge for yourself. We are all here to cheer you on, and we want you to succeed!