What product are you currently wearing? As you mention your leaks go up the back, it may be that you are fitting the product too close to your privates, which means the product doesn’t get chance to absorb the liquid. Try folding the product in half length ways, then squeezing along the folded edge before fitting. This activates the leakage barriers and forms a place for the urine to run into. Make sure you don’t push the product too tightly or close to your privates.
If this is not the case, try using a pull up pant or all in one if you don’t already. This will cover your body more than a regular pad.