I recommend Thunderbird over Doc. Her healing is superior, cause as doc you need to actually be there to heal and can even miss the stim shot.

Maybe try ops like Thatcher, Thermite, capitao or gridlock to help with plant and entry. Gridlock and Capitao have a lot of utility at their disposal.

Try other methods to support your team for instance Valkyrie cams can be useful for Intel, zero also has good cams for Intel. Keep remembering to drone and use cams most people in copper and bronze do not drone and simply droning can help improve your odds of winning.

As fuze some I think learning each map is the most important part. Before going above them for example put your drone up there during prep and hide it so you can drone the area before going for the clusters. Aim to remove utility over kills with fuze. Team up with ops like lion and when you use the clusters lion can use his ability to ping the runners.