I remember This being a good thread. May helps a tad.
Essentially, you want to run your fingers along the front wall until you feel a solid surface, positioned horizontally under the tissue (this is your pelvic bone). You want to keep going and run round the far edge of this into a depression. Then the g spot is basically here somewhere. Usually feeling like you have to pee when you apply pressure is a good indication your in about the right spot as its adjacent to the bladder.
Anatomy does vary though so making circular motions with your fingers over the tissue and working your way back is a decent plan.
Its easier to find when your aroused as blood flow increases the sensitivity.
Ps. It took me 14yrs to find mine, so your not alone.
All else fails, getting a decent g spot toy is a good plan B