Vitex/AC messing with ovulation?

Been taking vitex/agnus castus since cd4. I'm on what I think is too high a dose (2g). I have had steady but not +ve opks for the last 4 or 5 days, teasing me into thinking they will darken, then don't. I'm doing 2 a day. 
I'm now at cd15 and yesterday had a temp dip and today a temp rise. Could I have missed my LH surge, even if I'm testing in the <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> and late am? I thought vitex increased LH levels? I'm worried it's actually stopping me from Oing, and I'm considering coming off it for a day or two then taking it again but only half a tablet. Any help?