As a fellow support main stuck in mid to high Gold I can confirm that a lot of the time your team is going to be the deciding factor for you, especially if you are playing Ana or Mercy. Playing solo especially your fortunes are going to depend on being grouped with other players who know how to position, how to work together, and ultimately how to take advantage of your healing. I would recommend picking up a third main that can be more of a flex support that can help carry in certain situations (Baptiste, Brigitte, Lucia are good examples), as it is much easier to carry in that role, and can help cover up a lot of mistakes that your teammates are likely to make. Personally I’ve had much more success going this route. Or if you want more specific tips on your play style as Mercy or Ana then you’ll have more luck posting VODs and asking for feedback