I am now 450 in Alchemy and I have not learned and recipes or transmutes even though I’ve made tons of pots and transmutes.
I don’t think there are any WotLK discoveries outside of transmutes. Most of the other “rare” recipes are learned via your research cooldown (a few are from BoP recipes).
For the transmutes, you really only have saronite to titanium to start with (and meta gems later), but if you did that like a dozen times while getting to 450, I’d be shocked if you didn’t learn any of the elemental transmutes–but it is still random, so there is always a chance you were just unlucky.