Overwhelmed with Stress: Job, Marriage, Health, and More

I need suggestions... I'm an overly stressed out 24 yearold. I worked a factory for 4 years before I left due to stress and mental health but now have struggled to find a job worth staying at. I'm currently waitressing but even though I like my coustomers I feel I'm always letting them down or my coworkers. to the point my coworkers walk all over my kindness... on top of that my boyfriend and I were given an option by his uncle for him to marry us next month or possibly not be able to be married by him. (he has cancer and the radiation may take away his chances to speak again). I told my boyfriend I am happy either way I'd prefer his uncle but I'm okay with going to a court house too. 😔😔 it's only caused stress and arguments. it's all been so stressful... but on top of it I was told earlier this year how I needed heart surgery to fix the main heart valve, because it leaks. they said it's not super needed right now but keep pushing my appointments back further and further. ... pushing back the time frame for me to try and have a family.... I just want to sit in a corner and cry all the time or sleep all the time. my 7 month husky won't allow that though. any ideas on how I can address any of this? I just want to be happy and do something good in my life but I keep failing and falling further behind... I don't have much support but my boyfriend is trying the best he can. 😭