Continue with your training plan and observe the taper. On race day, pace correctly, eat right, and have just a bit of luck on your side (no mechanicals, no accidents, no injuries) and you'll finish absolutely fine.

Training is about more than just doing centuries and 4k swims. Have you been consistently following your plan and recovering? If so, don't sweat what you haven't done in training. Just make sure that when those workouts are on your plan in the next 4 weeks you do them. I've only done 1 century so far this season per my plan. I have 3 more to go. I have yet to do a 4k swim either, though those are definitely coming up.

FWIW, my HIM PR last year was 5:37 and I finished IMOO in 12:36.

Your training sounds right where mine is for IMC. Come race day, my longest bike will be 90 miles, swim 3600 meters (not a straight effort) and run is 17 miles. I only raced one sprint and one HIM this year and just focused the rest of time on my IM training. Race day success will be more about nutrition and pacing than whether or not I rode an extra 10 miles on my bike just to say I've ridden a century. IMC will be my first 2.4 mile swim, my first century and my first marathon. Based on your post I would say you are right on target for race day.

Remember that the first IM should be about having fun and finishing strong. It sounds like you've been focusing on training because you had good results for your HIM. Continue to follow your training plan, hit your taper and on race day have faith in your training and enjoy the pay off.

You will finish with no problem if you follow above advice and watch your nutrition and pacing. Speaking of pacing, in your HIM you did a 2:34bike and a 2:04 run. Your run is slow compared to your bike time. Did you push hard on the bike and have trouble holding pace on the run? If so, you should definitely take the bike easier in the Ironman. Otherwise the marathon will be a big problem.

jhudalla-

I am right with you there. I am doing IMOO soon and this is also my first IM and I am a little nervous myself since it is a really long distance. I have yet to do a 2.4 mile swim or any of the other distances yet; I did do a HIM recently at 5:37 and I felt strong afterwards still. But I am following the current training program on this site.

But I guess there is always uncertainty when we go for another distance especially for an IM. I guess the fun part is the "not knowing"...

Oh I'm sure.. I was cruising for the first 7 miles of the run, but couldn't do anything more than a run walk for the last 6 or so. If that was 6 + another half.. good grief.