Amanda - I think you are fine. I was 11.7 on Day 24 (6DPO for me). I just pulled up my actual lab results because I remembered they have the acceptable ranges for each phase of your cycle. I typed them up for you below.
Follicular: 0.2 - 1.4 (this is for pre-o)
Luteal: 3.3 - 25.6 (this is for right after-o; your 4.3 is in range)
Mid-Luteal: 4.4 - 28.0 (this is for between o and AF; your 12.88 again is right in range)
Pregnancy 1st trimester: 11.2 - 90.0
Pregnancy 2nd trimester: 25.5 - 89.4
Pregnancy 3rd trimester: 48.4 - 422.5
If it makes you feel better - your 12.88 is not only great for the mid-luteal phase, it qualifies you for possible 1st trimester pregnancy!!
You have plenty of progesterone to make a beanie stick!!
Hope this helps - good luck!!