How do I get my skill past 375??  ithought that was the max but I am seeing recipes that take a skill hagher than that.

I could be wrong(I'm not a high lvl alch on any alts but I'm pretty sure 375 is max till wotlk gets here

There are some equips that increase alch. You will need them to past over 375.

I am at lvl 48 and my alchemy skill is at 300 but i cant find a trainer to get me higher. any suggestion

you will be needing to go to the outlands where you will be able to get higher skilled.
If i'm right you will be needing to be lvl 55 also.

Currently 375 is the highest you can have for alchemy.  You learn past 300 from the guy in the tower at honor hold for alliance.  There is also an alch trainer in shat in lower city and also an alch lab for making flasks.