Boil off

I have a large aluminum pot that has an 18 inch base, I was anticipating a large boil off so I have a little over 7 gallons for my 5 gallon batch. It was even larger then I though so I ended up with only about 4.5 gallons of wort. I just pitched but I am wondering now if I should add a have gallon or so of spring water.
Also if I do nothing I anticipate this means a much higher alcohol content then expected (broken hydrometer)
I did a bunch of things wrong with this batch including possible contamination, so it will probably be my best batch so far

Lucky you, same thing happened to me today. I came up with 7 gallons of wort and it was boiled down to 4.5 gallons. I pitched and forgot it. I wouldn't add any water to your wort, but that is my opinion. I'm happy with 4.5 gallons of beer.

I made some mistakes too. I hope we both made epic brews today.

Thats a pretty high boil off rate, try turning your burner down some.