Oh, you are flying a Slo-V in wind? That is not a good wind plane.

Try this:

1) Move CG slightly forward
2) Go to 7 cell battery - both stronger and a touch heavier
3) Keep your climb angle shallow to keep your speed up.

Lift is generated by air speed over the wings. That is, your ground speed + the speed of the air moving over the wings from the breeze. The more wind, the more of that air speed comes from the wind component.

If you nose up, you present the bottom of the wing to the wind which then pushes you back. You need to keep the nose mostly level and move it from a little up to maybe even a little down in order to keep your speed up.

This is not a techincal aerodynamic description, but more of a visual description. You can't really climb if the wind is pushing you back. You must hold your positing or move forward. Try keeping the nose more level, going 7 cell and perhaps add some weight.

If you are already at 7 cell, strap on a second battery on a windy day, just for ballast. That might be too much, but what it will do is allow the plane to fly faster, up to a point.

Glider pilots do this all the time.

Let me know your results.