Bundleofjoy yes you can take juz 21, it's not taken yet.
Wantababy, I am not an expert in any way, but your beta seems very good for 16dpo. You don't even know when you ovulated, so try not to read too much into this stuff, but still maybe it helps:
http://www.americanpregnancy.org/dur...hcglevels.html
I know nothing about progesterone levels. Again I am putting a link here:
http://www.americanpregnancy.org/pre...evelopment.htm
Sister, please don't worry.