Yield Problems (

I'm new to brewing and have only 3 brews under my belt. I decided to jump into all grain from the get go. Most of my brew days went pretty smoothly hitting my mash numbers and coming semi close to most of my OG targets. The one major problem with all three brew days was my yield. I've hit between 4 and 4.75 gallons total yield on all three. I used a mash and sparge water calculator from Brew365.com and set it for a 5.5 gallon target yield. My last brew was a pale ale that called for 1 1/2 oz Cascade and I used dry whole leaves. Between that and the whirlfloc tab I used I noticed a ton more trub than I accounted for. Are there any tricks or tips anyone can give me to help get me on the right track here?

There are several places where you lose volume. Are you properly calculating all of these:

1) Grain Absorbsion
2) Boil-Off
3) Trub Loss (both post-boil and post-fermentation)
4) Evaperation during cooling process (ice bath/chiller)

The numbers are different on different equipment and with different grains, but for comparision, on my equipment I lose about 0.7 gallons/10 lbs of grain, about 1.2 gallons/hour boil off, about 0.4-0.6 gallons loss to trub, depending on beer style/ingredients, and about 0.4 gallons/hour to evaperation during my post-boil ice bath.

So for an average 5 gallon batch, I start with 5 gallons + 0.7 + 1.2 + 0.4 + 0.2 (30 min cool down) = 7.5 gallon starting volume.