Hi JanaLaine,
Nice documentation of what You want to do!
But if my old eyes don't trick me, You mixed up the + and - of the 12 Volt supply to Your "external" valves.
0V must go to - minus of Your Valve coil and the + plus 12V get switched by the relays contacts and than must be connected to the +plus of the valves coil.
(+0V as You write is yes the Zero of the + PLUS 12 Volt supply, but "more" negative then the plus 12 Volt.)
rgds