I'm 1.5 years into my master's and haven't finished my proposal, how do I push through?

For context, I didn't exactly set myself up the best going in to grad school. I went straight in after undergrad (literally finished my BA the term before my first term of grad school), had 3 jobs my first semester, and up until now I had the most intensive TA position. I was going to take my last class requirement this term, but my grandmother passed and one of my partner's pets passed around the same time, so I dropped it as it was overwhelming. I still haven't finished my proposal, I've been working on it since July. I just felt I needed to do major revisions, and now it's hard to make myself look at it. I'm also AuDHD, which doesn't help. I'm very burnt out, if you can't tell. :') How do I get through this and finish? I know I'm definitely going to have to take a 3rd year, and unfortunately I can't take a leave until this September because my funding that's keeping my partner and I afloat as he struggles to find work requires me to be full time. I apologize to my committee members whenever I see them, and I have been told that it doesn't matter to them how long I take (and my supervisor is so busy I think he forgets about me sometimes), but I feel like I'm wasting everyone's time, sympathy, and money. Any advice?