Clearly they didn't get easy basket on your 19 t/os, because they only shot 29/64, 45%. If those 19 t/os generated into 15 easy layups (assuming no putbacks), it would mean the team was 14/45, a dismal 31%. If the 19 t/os led to 10 easy baskets (which wouldn't be easy baskets by your metric, considering you think 50% is low...), the team is still only 19/45, or 42% on the shots not generated via t/o.
The turnover differential was 6 in their favor, but you won the rebounding margin by 5, fg% by 4.7%, 16 extra free throws, and won the foul battle by -11.
Honestly, if you shot 5-10 3s, or ran uptempo (get your opponent deeper into foul trouble and force the FR to play more minutes), you would have won by 5-10 points.
And no, you would not shoot 20% from the 3pt line with players sub 65 per. You would shoot something like 28-35% with per around 60.