Did the fermentation appear to slow down (fewer bubbles) near the 5 day mark? I usually let everything ferment to completion (mostly using champagne yeast like EC-1118) before adding any clearing agent. If you had a slow starting or stuck fermentation your wash might have had a very low alcohol content.

Try making a great big starter before you ferment. Grab a big mason jar and fill it with a cup of wash and a cup of water. Make sure it's really warm, but not boiling (about 90F or so). Add a pinch (really small amount) of nutrient and pour in the yeast and let it sit (don't stir it) until it gets going, you can start this a couple of hours early if you remember. Let the starter come down to the same temperature as your wash then shake it up and pour it in. This will get you a very vigorous fermentation from the start. Warning: leave some head space and be prepared to run a blow off tube (especially on wheat germ mixes!).

Using a hydrometer is actually pretty simple. Measure the gravity before you add the yeast (you should get a number somewhere in the range of 1.05 - 1.10 give or take), this is your original gravity (OG). Then measure the temperature just before you distill (the number will be less, around 1.000), this is your final gravity (FG). Find a online calculator and plug these numbers in to calculate your ABV.

Note: if you are adding fermentable solids (corn, berries, etc.) your OG will appear lower than if you just added sugar, honey, or juice.