So I recently just tapped into my stout I'd been fermenting for a while, but it really doesn't have much in the way of maltiness or mouthfeel. And no wonder, either; I've taken to calling it my "If It Coulda Gone Wrong Stout" due to the numerous mistakes made when brewing it. The biggest mistakes were forgetting to mash the flaked barley, leading me to spend an additional hour converting, and then following up by oversparging so I ended up with 6.5 gallons targeting a 5 gallon recipe.
But why not boil off that extra volume, you ask? Well, I had decided to try the "first wort hop" technique that I'd heard advocated, so I couldn't boil off any longer to get down to target (Incidentally, this was the only success with this beer. Fantastic hop character out of very few hops). I partially resolved the situation by freezing some of the beer, and then collecting the first half of what melted, which got me down to my 5 gallons, but by then it had already fermented very dry.
So basically, without adding malt extract and restarting fermentation, is there any way for me to add some body and mouthfeel? Would either lactose or maltodextrine help?
Thanks in advance!