I think that 19.2 is fairly good for 12 dpo. My naturopath/midwife said that they like to see the levels around 25 but anything from around 12 to 90 is "normal". Mine was 15.2 at 10 dpo and she put me on progesterone. BUT, I had a short lp and bleeding/low progesterone with my ds so it is more of a preventative measure than anything. I think if my history wasn't like it was she probably wouldn't have suggested adding progesterone. BTW, my levels still only got up to around 22 with ds when I was on progesterone supplements.
And this is from webwomb.com...
10 DPO: 10 - 50 mIU/ml HcG
13 DPO: 20 - 100 mIU/ml HcG
16 DPO: 40 - 200 mIU/ml HcG
19 DPO: 80 - 400 mIU/ml HcG
22 DPO: 160 - 800 mIU/ml HcG
Looks like you have good numbers!
(Becky, sure your not having twins??? Your numbers are high according to this...)