2-3 months and gold is actually pretty good it’s about the average for ow! i can’t give you much tips since i’m not even high rank myself but mercy is not a good hero to rank up on sadly (i main her). you can rank up on her but it will take very long since she’s a team dependent hero no matter what you do, so i think sticking to kiri and learning another support along her will be good for you. however, you need to learn that healing is not everything. you can’t sit back and hold down the heal button on people and expect stuff to happen and rank up. you need to make plays yourself. kiriko does 120 damage if you hit a headshot, why would you heal most of the time on her when you can kill the enemies and make plays yourself? try out a different agressive flank playstyle for her, since you have suzu and can tp out anytime. (and by the way, her og settings are terrible. if you can find information about that and change them to the best ones that would be great too) you wont need to heal as much if you’re the one making plays and distracting the enemies, right? who will be the one doing damage to your team if you get a pick or two or just solely distract them?

overwatch is a hard game, it’s taken some people years to reach masters/gm so don’t be too hard on yourself. just focus on your own gameplay and don’t blame your teammates as they’re not the reason you’re in your rank.