this doesn't seem like anywhere near enough nutmeg or angostura bitters if you go by the recipes that make jasper's mix!

Agreed. Jasper's 'secret' mix, from Jeff Berry's telling, is 8 oz lime juice, 6 oz sugar, 0.5 oz Ango, and 1/2 a grated nutmeg (for a half recipe). This turns out to be about 1/2 to 3/4 of a tablespoon of nutmeg. Makes ~10 oz of syrup, so more Ango, and LOTS more nutmeg.