FFS woman you're a parent already, except it is isn't to a sweet innocent but a grown arse man. You are partly to blame for this dynamic, this is who he is and I wouldn't bank on him being different any time soon.
If you feel like this now imagine what is going to be like with sleep deprivation and your delicate flower of a partner complaining about not having enough down time. Imagine what it will be like returning to work earlier than you'd want because your partner doesn't have the will to step up. He already expects you to look after him and his business, I'd hate to think what he's going to
You've enabled the very opposite behaviour that you want in your partner. If you feel unsupported now can you imagine what it will be like
There's no evidence that your partner will step up in the future but plenty to suggest that he won't. If you insist on having a child with this delicate flower then be prepared, in terms of financial and parental responsibilities, to be a single parent.
This kind, sweet 'great dad' description doesn't quite match up with him being content for you to carry him financially and your fears of him being a not very responsible parent. .
The concern and worry you feel now, won't magically disappear upon motherhood but in the midst of ehaustion, hormones and stress about paying bills, they will strengthen.
It's time to take a step back because there's nothing lonelier than being a single parent, whilst in a live in relationship with your child's father. My Ex was also a potentially great dad up until the moment I realised that I was expected, (and reluctantly took on the role) of the responsible parent and his role was that of glorified godparent (occasional fun stuff but me always being on hand to take care of nurturing and always to be handed back full responsibility at the end of the evening).
I think deep down you know that your partner isn't great father material but he's on 'on site' and you are so used to being the responsible one that your willing to ignore the glaringly obvious issues you have with his character, in exchange for convenience and familiarity.
Don't confuse the person you want him to be, with the person he actually is.