I think you are being pretty tough on yourself. How many people do you know who ran a marathon, completed a triathlon and lost 40 pounds? (all whilst having to cope with the upheaval to their routine/diet of being diagnosed with diabetes)
You are in a small percentage of people who set out on a journey at the beginning of last year and can be judged as a success. Sure you might have wanted to lose more weight, run faster, tri harder etc but there's no way anyone would judge your year as anything other than remarkable. Many more people are still sat on their arses dreaming about being more active, you are out their doing it. It's your first year too so your only aim should have been completing.
Take a look at all the fast people you know and how long they have been racing? Much longer than me and you! We'll be challenging in a few years though!
Your plan looks pretty good. All the races after the Connemarathon build up nicely. Perhaps because of that the first one looks a little out of place (?)
Oh, as has been said, join the S/B/R challenge. it's pretty motivating when you look at the work others are putting in and it makes you want to up your game.
I feel a little more positive after a good run at the weekend.
BUT the weekend is still annoying me and i might have to look at my meds.