It's all trial and error; and remember the whole DE or straight razor wet-shaving thing is based on the assumption that you can't expect perfect results right from the start and need constant practice to reach the perfect shave.
One last comment: Someone suggested Williams soap.
Williams is a love or hate affair and IMHO it is not easy to get a good, long-lasting lather from Williams (I am sure some Williams lover will contradict me; hence the "IMHO"). Williams seems to be particular dependent on the right water/soap ratio and that is exactly where you appear to be struggling with.
If you want to taste the sweet fruit of success earlier, stick to creams like Nivea, Proraso and the like.
Some people may even suggest that for that very reason you should start with Williams.
"If you can lather with Williams you can pretty much lather with anything."
If that concept was true, driving schools would all have Ferraris, wouldn't they?
"If you can drive a Ferrari, you can drive a Civic, no?"
B.