We had trouble conceiving DS (5 years ago) because of my irregular/non-ovulatory cycles. While I haven't truly started TTC again, I can tell you that just after losing about 20 lbs (I have much more to go, honestly), my cycles are like clock-work, which leads me to believe that I may actually be ovulating normally now. This is due of course to the decreased weight/fat cells/ whatever - which you will find true with any other weight loss plan out there. Metabolic has worked for me, though, so of course I'm a little biased about that.
As far as the herbs and such, for the most part I haven't learned of any that will directly affect your fertility. If you do get pg while doing Metabolic, of course you'd want to discontinue the herbs, but I can't think of any reason why you shouldn't take them even if you're concerned with fertility issues.
I hope you find the answers you're looking for! Good Luck!