4 levels at 6dpo on 50mg clomid (clomiphene) were 12.9 & 10.8. does this indicate poor egg quality or make fertilization more difficult? i'm on 100mg this cycle.

No worries: Progesterone levels in a cycling woman are either ovulatory or non-ovulatory. If your level was over 1.5-2.0 you ovulated, if level is below 1.0-1.5 you didn't, or at least you didn't yet. People (doctors and patients alike) mistakenly try to use early ( 6 days) p4 levels to decide if a cycle is 'good' or 'not, ' the levels don't tell you that.