Sounds like you might be rushing her into the air. Do you pick the tail up (push on stick, or trim it to do so) on the rollout? Doing this will let it get more speed on the ground to about 120-140. From there you can relax on the push just a bit and she will fly when she is ready and should feel considerably more stable because of it. Also, do not use flaps IF you have been.
If she still wants to pick the nose up, do not let her, keep it down (and use more nose down trim next time) and the climb slight till the airspeed picks up more.