Actually, I use 20ml of liquid for an 8x10. I just base my sensitizing on the strength and amount of stock solution (5ml of 8%) that I then dilute 1:3 with acetone (5ml + 15ml). If I was using alcohol instead of acetone, I might use it 1:2 (for a total amount of 15ml). Acetone evaporates so fast that I like using a little more than I did when using alcohol. But in the end, I am still delivering 0.4 grams of dichromate per sq inch (a nice mix of units there. LOL!)
I have seen such highlights as yours in workshops I have given. There has been two causes that we were able to correct. 1) digital files that clipped the highlights. or 2) too low of a concentration of sensitizer (not enough dichromate) used to compensate for negatives that had too low of a contrast range.
In your case, it just sounds like your negatives have too much contrast for the B&S tissue, but without seeing the negatives, I am not 100% sure of this.