When do the training wheels come off?

[Lmcgyver]

MP, there’s my issue...by the time I would use flare I was usually completely out of mp. Yup, I got some practicing to do with trust...

Unlikely. It's far more likely that you used up your Umbral Heart (or hearts, plural; you say you used Freeze multiple times?). One of BLM's level 68 traits reduces the cost of Flare by 1/3rd when under the effect of Umbral Heart, and completely removes the status when cast. As a result, using Freeze once will be sufficient to use two Flares so long as you cast no other Fire spells in Astral Fire - one MP tick under Umbral Ice III is more than sufficient to cover the MP cost.