... and increases the amount you get healed by a %...
Expertise increaes the healing you do, rather than the healing you receive.
Otherwise, fair enough.
High PVE stats can mean you'll have a big health pool in PvP, or do big damage/healing numbers. But you'll take a pasting from someone in proper PvP gear, because they're mitigating all the damage you do and multiplying the damage they do, and your big health pool just means you'll need more healing to get back up to max.
More often than someone in top raid gear though, is someone in bad PvE gear, who will swiftly become a pink smear. Jumping into a warzone in your levelling greens when you've just dinged 50 will probably hurt - get the Recruit set of gear instead. Then buy your War Hero gear with the comms you earn (can take a week, a piece or more per day depending how offten you PvP), and try to learn to play a bit in the meantime, while getting your arse kicked as little as possible.