I personally have 2 1.4 groups for 6 snakes, and I can't make them fast enough.... ASF's grow very slow. Everything else sounds about spot on from your OP. The only thing I didn't see you touch on was the temp your keep them at. They like to be on the colder side, about 70 degrees F. My females usually put out about 8-15 babies every 6 weeks. Then you are looking at a 4-6 weeks grow period before you feed and they will be around 30-60 grams at that point. Rule of thumb for weening is once their eyes open.
My suggestion is to build one of those racks with the cement tubs you see everyone posting and keep them breeding like crazy. They grow so slow and ASF's can never get too big for a BP. I'm holding back a couple more 1.4 groups to have more growing out because I always end up not having enough. 4 females for every BP might be a tad much, BUT, like I said they can never grow to big for a BP to eat.
Hope this helps.