Gypsum Calc. Chloride Epsom Salt CaSO4 CaCl2 MgSO4 1.5 4.2 3 2.0 5.5 3.9 13.5 GALLONS BEFORE SPARGE stop at 3.7 gallons
Based on boiling 13.90 gallonsliters at 1.046 for 90 minutes, this will decrease your wort by 1.50 gallonsliters, bringing your after boil OG to 1.051. You wanted an OG of 1.054. It looks like it will be under.