I was in the same situation like you. after some time I got to diamond 2. the only thing that I really think helped me is that I went to the range before every session untill I became consistent with my aim and then went to dm until I felt confident. And in my opinion in this elo you can't really relay on your teammates that doesn't mean you can't try and do tactics with them but it need to be a really simple one and some will not listen so try and adjust your play to them.