Brew in a Bag? Sure and many do it. Get a fine mesh grain bag and you may even decide to stick with it long term.
1) You can drip sparge like you did (kind of a sprinkle tinkle).
2) You can no sparge. You can minimize some of the efficiency hit of no sparge by going to a more dilute water/grist ratio.
3) Or you can dunk sparge where you dunk the grain bag in a second vessel at 170F for 10 minutes. Combine first and second worts prior to boil.
I've seen the best efficiencies (upper 80's) with option 3, but option 1 gets me low to mid 80's usually and is less work. I use a frier basket, rope, and pulley to suspend the grain bag in place. Just look at the BIAB sticky for technique info. With any of these 3, you need to squeeze the bag as much as possible to pull out most of the liquid. A saucepan lids keep your hands cool and clean.
Primary #1: Empty #2: Empty
Secondary #1: Berry Rhubarb Wine #2: Black Currant Wine #3:Border Crossing Vienna
Kegged: Orange Pale Ale IV, Hidden Lake Nut Brown
Bottles: 2H IPA III, Carmel Apple Cider, Spruced Winter Warmer, Surly Bender clone, Big 50 Barleywine, Framboise Lambic, Dark Belgian Strong, Kicked by a Moose Scotch Ale, Russian Imperial Stout, Sparkling Elderflower Wine, Barolo Wine, On Deck: Ice Shanty Bock