How do I get out of Bronze 😭

This is embarrassing but I just started playing competitive and cannot get out of bronze III. 7 straight losses. I was the only healer the last 6 games, no tank in half of those, and at least one person has quit each of the past 4.

I’m not the best player, but I do my best to ping and communicate. I consistently have the most healing and least deaths in every match, even led my team in eliminations twice. I’ve threatened to switch to dps if nobody tanks or helps heal, and nobody switches. I’m not a great player by any means, but I’m sick of spending half the game running away and healing dying teammates.

Do I just need a full squad to advance in comp? Any tips as a solo queue healer (Cloak & Dagger, Luna, occasionally Loki)?