You almost certainly did a better job. Time=money, so most painters only do what they have to do. You worked at such a leisurely pace that it almost sounds like painting the house was your entertainment for a month, so additional savings there.
There is about to be a paint shortage and costs are spiking. Sounds like you chose an excellent time to get this project completed.
Paint shortage?!? Source please? Parents still need to paint 3 rooms...
Edit: googled it. Interesting, I haven't seen any evidence of shortages when buying paint this summer. Of course, I'm also not pulling cans off the shelves to do the color mixing, the staff is. So I'm not in the stacks much. And most of the primer I've needed to buy was oil based, which is much less popular.
I was getting paint from Sherwin-Williams a couple days ago, and their shelves were almost completely bare. They were out of anything 1gal+ in all but their most popular lines.
Conversely,Lowe's/Home Depot's shelves are completely stocked with Valspar/Behr/PPG, and the local Benjamin Moore store seems to have a robust availability, so I think it's really variable by region.
As for OP's question, my new neighbor actually used to paint houses professionally (mostly him and a couple hired hands). Since it's impossible to ballpark something without seeing it, he told me that he'd typically pull about $100/hr profit after materials - but that would also vary depending on how much help he had.
He'd do at least a coat a day on a house, maybe two depending on the size of the house and the climate conditions. I have no idea how to forecast how much time it'd take him total but if you invested 120ish person-hours, a pro with a sprayer and a hired hand could probably do it in 25-50 hours, I'd guess. So with cost of materials and targeting $100/hr, you'd probably be in the $5k+ range like you estimate.