Please help I can’t escape bronze

I really don’t know what’s going on here but I desperately need help. I have been stuck in bronze for so long. I’m level 30 and I’m a cloak&dagger Main. I’ve spent about 50 hours on the game and about 25 of those are in competitive. I have been stuck in bronze for all phases of those seasons, my career highest is bronze two. I’m averaging 30-45K heals per game (average says 17k per 10 min) and I don’t think damage is horrific. I’ve only won about a third of my matches but no matter what I do I can’t get out of bronze. I played with my boyfriend (in plat) who says that he thinks I’m pretty good but that I just keep getting unlucky with my teams and I have to keep pushing through but I’m starting to lose faith and playing because I just feel like I won’t progress at all. I’m on like a five lost streak right now. Any help is greatly appreciated I’m totally open to admitting when I suck and I totally have my games but I thought I was doing good and now I’m starting to think I’m the problem again. Please help