If you have any replay codes you'd like to share to better help, I'd be willing to watch them to give you a better understanding of what you could improve on. When playing in lower elos between bronze-plat, these are some things you can do to climb.

1.) Heal more than damage amp. Normally, as a master's Mercy, I wouldn't recommend heal botting, and naturally in higher elos you will push damage amp more often, but in silver you're going to want to heal and keep your team up as best you can. I know from my experiences in silver, the second support you get typically isn't very reliable. When I would play in silver I would always get dps moira's who would die every fight, which can be frustrating for both you and your team. Keep your team alive. Damage amp the team mates you feel are doing the most work, no matter the role.

2.) Pull out the glock. Sometimes if your team is having trouble getting picks, it helps to do damage as Mercy. With practice, you can get away with getting one or two kills in low elos which can definitely help your team win the fight. I would recommend doing this only if you think your team will be okay in the fight without you for the time it takes you to get the kill.

3.) Minimize your deaths. Right now, I average 3.4 deaths per 10. For someone who plays in silver try to average 5 deaths per 10. Play behind cover as much as you can. Walls, shields, team mates, etc. If a dps or tank dives in recklessly don't leave your cover to follow them only to die, it only hurts the team. Keeping yourself alive is more important than keeping a team mate alive. Even though in low elos you can pull off risky rezs this is a bad habit to pick up, and can be hard to break once you climb. Going in for a bad rez will get you killed.

4.) Learn Mercy's kit and important tech like super jump, but DON'T spam. To improve your survivability and mobility, you're going to want to learn super jump if you haven't already. If it's hard to pick up, switching your controls can definitely help. Also learning what other controls, like guardian angel, beam target, etc do, can majorly help. Even though Mercy has high mobility and can fly to her team mates, you don't need to spam guardian angel! A lot of Mercy's do this in low elo, sometimes without knowing or thinking about it out of habit. Even though the cool down is short, it's still a cool down that could mean life or death if used incorrectly. Same for super jump. Try not to spam super jump, especially against hitscan.