Stay with the factory volume for fork oil until you get things sorted out. The forks have 2 springs: one is the metal coil spring inside, and the other is the trapped air above the oil which becomes a spring when the fork compresses. Add too much oil, and the resulting pressure can damage the seals. Ride height cannot be corrected with oil volume. Don't confuse damping with springing. The ride height and geometry has zero to do with damping. Your change at the back would create the same stability issue if you take the oil from the shocks and have zero damping. The spring, which determines the position of the back when you are on the bike would be unaffected. Certainly when you are riding the situation is dynamic and more complex but you made one change, and created one problem. Guess where the problem comes from. Put the old shocks back on, sit on the bike, and measure from the ground to the top shock mount. Get help, make sure the bike is on level ground and perfectly vertical (measurements should be the same on both sides). Put the new shocks on and repeat. If the new shock measurement is higher, you need to either lower it somehow, or raise the front the same amount to maintain the original geometry (technically it won't be, but it will be close enough). Commonly guys raise telescopic forks by using a longer preload spacer, usually under the cap on top of the spring. If you have spacers, make appropriately longer ones from pvc pipe, or you may be able to add them if you have none. Stronger replacement springs would do the same thing, but more complicated to figure out, and of course more expensive.
