Yep, you need a bigger fermenter.
The formula for estimating the gravity effect of blending is as follows:
Vt*Gt = (V1*G1) + (V2*G2)
Vt is Total volume
Gt is gravity of total
V1 is volume of the first amount
G1 is gravity of first amount
V2 is volume of the second amount
G2 is the gravity of the second amount
So you have 2 gallons of water and 1.25 gallons of honey (roughly) and which will give a V1 of around 3.25 gallons - your gravity was was 1.150, but it theory could have been a little higher (like 1.160).
The Berries will add roughly 1.25 gallons of juice and the gravity will be somewhere between 1.030-1.040.
So you should net out about 4.5 gallons as a Total Volume (with the pulp gone) with an effective starting gravity somewhere in the 1.115 to 1.125 range so if it goes completely dry (as it should) you'll have something like 15.5-16.5% ABV.
Nice and strong.
It should be good.