Solaray is a great company, I think those would meet my docs criteria for high dose. I'd clear all your supplements and OTC meds with a doc, just to be on the safe side. I just use that as a general disclaimer, because I want no responsibility for someone else's pregnancy.
PM me an email address and I can send you an elimination diet plan, I downloaded one awhile back for me and Hubster. I can't attach it here because of the file size. My stepsister was on an elimination diet for the entirety of her second pregnancy, so I know it can be done safely - I think you just have to check it out and plan what to eat in advance, so you aren't left hungry or without options. I would say it's a very easy thing you can do on your own to see if it improves things for you.
The closing of your post, referencing all the statistical stuff, sounds like something I would do in your shoes. Try to take some comfort in the fact that your odds are as good as they can possibly be under the circumstances and it will be what it will be at this point. FX this works out for you!