Upcast, it's 9 dice. Treating 1 as 2 (Elemental Adept) means the dice get results of 2, 2, 3, 4, 5 or 6, for an average of 3,67. Among those dice, you'd be able to reroll 3 at most, which results in a possible roll of 3,67 (1, rerolled), 3,67 (2, rerolled), 3,67 (because technically you should reroll 3s as well), 4, 5, 6, for an average of 4,33. So your average damage is 3x4.33+6x3.67 = 35. Plus Elemental Affinity (3) and 8 radiant soul damage, that's 46. Supposing you actually can have 16 CHA, 16 CON and 16 DEX with your build. There is no way you reach 55 without adding Radiant damage twice or being in Counterspell range.