"I lost interest after that."
Yet still posted! Didn't your parents ever tell you what to do if you don't have anything nice to say?
I had my first at 33 and was beginning to feel a little like an older Mum OP. I think that when you're at an age where you're married, settled into a career and thinking seriously about having children, you do feel old and therefore, older than that is really old.*
I understand where you're coming from as if you're after 3 then you could easily be in your early 40s when the third and final comes along. pregnancy when you're 35-40 is much more dangerous for you and for the baby so of course you want to move it along.
This is of course a conversation to have with your husband. Put your point across but he's probably enjoying life as newlyweds without children. Equally understandable.
If he's so keen to have 3, explain you'd rather have them before x age and so, the longer you wait the fewer you're likely to have. FWIW, after 35, 20% of women struggle to conceive.
*some posters look to take offence. 40s is fairly old to be pregnant.