You probably do need more mics,
OR (and this will look really stupid) You need a hard reflective surface under the toms to bounce the sound back up to your oveheads. (I'm assuming you're using overheads with a snare and kick mic, right?)
You need to jury rig some dense plywood to act as reflectors.
There are probably less stupid looking ways of doing it, but that's the only one that I know of or can think of right now.