You lost because of a basic tactical oversight, nothing to do with the planning. I think the way you are talking about the game shows you are on the right track. You know one way you can improve at least (planning). One thing does occur to me here - there are standard plans in standard positions. These have been worked out over years of analysis and OTB practice. I dont know the ideas for both sides in the Taimnov variation, I dont tend to play this way, but you should follow the normal plan, and then you have a framework of what to do when your opponent deviates. Basically, are you following the correct plan? OK, its been stated before that 'a plan' is better than no plan at all, but that will only get you so far. It appears that you start thinking for yourself on move 5. This is very early in any Sicilian defence! Unfortunately, learning book moves in such sharp openings as the Sicilian is a necessity these days. I also noticed you had threats if you pushed more pieces at his king side - possible N sac on f6, swinging a rook over to join the Q. That and the way you lost suggest maybe look a bit more at tactics first, then the planning will be easier and you will have more ammo to carry out your plan.
Best wishes.
As my book recommends always developing pieces and playing according to a plan, I tried this concept out with my trustworthy Chessmaster. This time against the personality Alicia(1423). I lost, and so I would like comments :) Thank you