So your initial strike gave you a 1.5 qt/lb ratio which is fine. Adding the additional 1/2 gal would have have raised it to 1.7 qt/lb, which is still fine. So I don't think it should make a significant, or even detectable difference in the outcome.
As far as your OG is concerned, calculating based on 5gal into the fermenter you achieved a 90% efficiency. This is pretty high for home brewing. If it doesn't taste astringent, then congratulations! If you did get some astringency through and you controlled your sparge temperatures pretty well you might want to look at adjusting your grind to make it coarser. You basically want just enough of a grind to split the husk. The more you shred it the higher your efficiency will be, but at the cost of possibly leaching undesirable elements from the husk.