So, at 3rd level, do you want the spell to be dealing 1d6+3 fire damage or 2d6+3 fire damage? As written, the spell does 1d6+3, but I assume, since that's the same damage the original Produce Flame spell would be doing, that you want it to be dealing 2d6+3.
Let's say you're a 10th level caster, giving you a duration of 10 minutes per level. You could hurl ten separate balls of flame each dealing 3d6+10 fire damage (or maybe 4d6+10 when you've corrected the mixup above), or you could "go nova" and create a 30ft cone of fire dealing... wait, how much damage? It looks like 20d6 as written, and I seriously doubt that's what you were going for. I think you need to cut the phrase, "+1 per caster level" from the sentence describing how much damage the cone deals. You also need to specify what type of action "blowing across the flames" takes. I would recommend making it a standard action.By blowing across the flames you may generate a 30 cone of Flame dealing 1d6 damage per minute left in the spells duration +1 per caster level. Using the spell in this manner immediately exhausts all remaining minutes in the spells duration.
Oh, and the cone of flame should probably allow a Reflex save for half damage.