it might just be your suspension. I've drifted (when i first got started) with a 35t motor and a 1900mah battery that lasted for about as long as I could blink. If your springs are too soft or too hard, it's going to be tough because you have either too much give or not enough over the drift surface. You don't HAVE to lock the rear diff, but it is recommended. Also, if you're doing it in your driveway, if you don't have a smoothe driveway, it's going to be tough to turn.
drifting isn't about power or speed. It's throttle control. With throttle control, you can do figure 8's in a 4ftx4ft area. And, clearly, you'll be going slow and they won't be long or HUGE angle, but with driver control, it's really cooler to watch than long sweeping slides that connect.
to get you started, I would try (from a standstill) turning your wheel and powering the throttle trigger. You should spin out. Keep doing that, but let off a bit every time until you do a controlled circle. That will let you know how much throttle you need to spin your car. If you can do that from a standstill, then you can definately be able to do that when you have some forward momentum. But, try to the cirlces at first and see how that works. Contrary to popular belief, drifting (well) isn't as easy at it looks.
GL.