DaveL,
Try doing a lock stitch like a machine and don’t make your SPI so far apart. You'll need a hand snitcher like the one sold by Tandy catalog # 1216-00. That one is not the best, but shop around and look for one like it. Depending on the weight of your garment leather, you should be able to poke the needle/awl though with out a hole. If you’re using BT-69 weight or lighter thread, try 14 spi and see how that works for you.
Roger