Where I'm from, 'pants' are underwear... so the mental picture of shopping for them with your dad was filled with all kinds of awkwardness.
I'm guessing we're talking about trousers here.
My advice to you would be to try different retailers. Some retailers only sell standard-length trousers; whereas others have shorter lengths. Men's trousers tend to be sold by waist measurement, but your hips are wider than your waist so measure your hips and use that as the 'waist' measurement. The only slight annoyance is that my hip-to-waist ratio is different than that of the average guy, so my trousers fit my hips but are baggy around the waist.
When I started my transition I spent several days reconning all the men's clothing shops in the various towns & cities I frequent, so that I could figure out who sells what. I'm in the UK (hence the pants/trousers thing) where there are retailers who stock shorter lengths for short guys - because there are quite a few shorter guys around here, I've noticed. I'm lucky to be able to get hold of 32" 'waist' / 30" leg length jeans in several different shops. The waist is also cut shorter to compensate for the shorter torso height of short men.
Another thing that works is buying tracksuit/sweatpants from cheaper, economy retailers. They have elasticated waistlines but they usually shrink in the wash (because they're cheaply made) so they wind up being the right size after the first wash.
