My (39f) partner (43m) won't do basic tasks and blames it on ADHD....I'm considering call off the wedding and need perspective.

We have been together for 4 years (we don't live together yet). We supposed to get married this winter. Something simple and small. Then the plan was that I'd move in with him for now and we'd look for a place to move to that would be more central for both our jobs.

He has ADHD (medicated) and he is successful in his work. However when it comes to basic tasks, he just simply won't do them and blames his ADHD. I am really understanding but sometimes it becomes annoying.

He simply will not clean anything. He does have a cleaning lady come once a week, so things are mostly fine, but there have been times when she's been away and in her absence he does literally nothing. She has been gone for 3 weeks (out of country) and during that time he just lets dishes build in the sink, he does no laundry, he doesn't change his bedding (and he sleeps with 2 dogs so there's fur everywhere) and he doesn't take out the garbage.

The one I have the hardest time with is that he will often be behind on invoicing clients. He doesn't want administrative help from other people (he wants ME to do it, but I also have a full time job). He doesn't feel comfortable working with anyone else. And the invoicing does take a bit of time, but it's really no big deal. And he doesn't get paid unless he does it. But over and over he just is months late and starts to run out of money (he also has issues with budgeting).

I find this stressful and it often will affect me (sometimes he needs to borrow some money just until he gets paid). Each day I'll ask him if he's invoiced, and he'll reply "nope". But he manages to go get his hair dyed. Or go get a massage. Or go to the dentist. Or yoga.

I try to be understanding, but I'm getting so tired of it. He acts childish about basic responsibilities, but he then will tell me he is able to be very successful at work (which is true...if he could budget he'd be well-off) so it's a trade off.

I'm at the point in my frustration that I'm considering calling off the wedding. And maybe even breaking up. But I'm not sure if that is just because I'm feeling stressed and frustrated and maybe there's a work-around. I go back and forth in my mind between "this is understandable for someone with bad ADHD and I need to be more sympathetic and patient" and "this is absolutely ridiculous behaviour for an adult".

I appreciate any insight, especially from those who have ADHD or are their partners.

tldr: partner has serious ADHD and just won't bother doing important tasks in his life, but is fine to spend time on his looks.