Yes, I've kind of been in this position. However, dd2 has been diagnosed with anxiety issues now this year (6yo) after years of me knowing something wasn't quite righ.
Then dd1 was diagnosed with arthritis (and after 10 months a full diagnosis has still not been made - cue lots of physio, hosp appointment etc etc.
I feel I have so much on my plate. I'm lucky to have a supportive dh. Dd3 and 4 seems ok thus far, however at 4 and 2 yo, they are still a massive handful.
I can't make the answer for you, I do understand the angst you are going though, I was lucky to eventually get dh on board with dd4, but this was before we'd had sought help over dd2 and we thought it maybe was just toddler issues. You sound like you have a lot on your plate and perhaps counselling would be of help. I see a psych for my dd2, but the sessions are really for me as I'm the one needed the space to discuss my parenting. We were reach to go down a private asd diagnosis, but psych says it is not asd (I reserve judgement).
I normally wouldn't say this, as I am usually supportive of having another baby if it is truly what you feel. If your family couldn't help on your last pregnant - would they now? Your partner is still depressed and there are money issues, you're seeking assessment for dd9 and I bet dd2 needs a lot of help too. My regret is that I not as good a mum as I would like to be, or can be, to dd1, 3 and 4; because I spend so much time with dd2. Tissues may be a situation you're familiar with.
I don't want to sound harsh, as it is really not my style, however, it might be nice to talk it over with someone objective? It's a shitty situation to be in, it's not at all nice for you to be feeling despondent when I bet you are the one always supporting your dh and dds 