Marriage is legal protection in the event of worst case happening. What happens to the OP and her DC if this bloke is hit by a bus? Do you suggest she harvests rainbows and hand rear unicorns to survive financially?
^^ Brilliant line
But also deadly serious.
I don't think OP has replied about financial situation - renting or mortgage, his employment / her employment. She is walking into a potential nightmare, and doing that with someone who hasn't got the decency to engage properly with her concerns, wants or security.
And as for the excuse about involving dd in the proposal! I've know people use a fluffy bear as a prop, I've know a dog to be involved with a ring on his collar, I've known a dad who dressed their tiny dc in a baby-grow with "daddy wants to ask you a question" printed on it. And I've also known many, many more couples where the proposal is without a ring, without any fancy theatrics or gimmicks, just a straightforward, honest, grown up agreement. After all it's not as if he has to be nervous that you might turn him down although maybe you should
What will his next excuse be? "dd reaching terrible twos and would be difficult at a wedding" or "let's plan for the next baby and wait till after that" or "need to save up for house / family holiday, not spend it on a ring or wedding"?
Or will he join the throng of "it's just a piece of paper" or "no-one needs to get married these days..."
OP you know what you want, and you've been clear about it. You know the discussions you had before you were pregnant and therefore the expectations that were set regarding marriage. Do not let him string you along.