My fermenter is too empty, how to fix?

This is my primary fermenter bubbling away in an unused bathtub. When I made it, I made a mistake and didn't get enough water mixted into the wort prior to pitching, and now I think I made a super concentrated batch of beer.

For those of you who are experts at this, I have two questions.

1) How much beer is in there? Thats supposed to be a 6 gallon pale, but I used about 4 and 1/3rd gallons of water and all 6lbs of the liquid malt extract, not sure how much that would count for in the quantity. There are no measurements on the side of the pale to indicate exactly how much is in there.

2) When I make my primer with sugar, am I OK to use a gallon (or whatever) of water instead of a pint in order to bring the volume back up to a normal level? I really don't think I want super condensed beer, do I?

Thanks as always.

Boil 1 1/2 gal of water for about 10 min now, let it cool, and add it to the bucket now. It looks like you have about 4 gal in there, maybe a little less. You will also lose a little bit of beer due to trub.

Is that bucket food grade plastic? Also, when your done with the bucket, take a gal jug of water and fill up the bucket, gallon by gallon, and mark the outside with a perm marker so you'll know for next time exactly how much is inside.

Its been fermenting for 7 days now, its OK to add water to it now? should I be very careful about sloshing around due to the trub, or is mixing it up OK due to the aeration for the yeast?

IIRC 6 gallons should get you to the botton of the botton ring on the top of the pail.

Don't add any water now. Wait until it is finished and then you can dilute with boiled cooled water after you rack to secondary or (best) at bottling time. Watch your finished gravity reading to see how much to dilute with. You should go for body and flavor, not nessesarly volume.