It's called procrastination---I think we all suffer from this sometimes, I do big time.
Buy the two bags, you probably will need them both, and you can match them to different clothes.

Use a pen, clearer and doesn't wear off or smudge .

If you feel better in the small T then go with it, I prefer the bigger ones, small makes me feel sweaty. The small will be an incentive to work off the roll, if not, who cars? Wear what makes you feel comfy and happy.