I'm in the same situation.
I'm already 34.5 yo so very close to 35 and yet not ready to move onto #3 just yet.
Personally I need to give my body a break from pregnancy and breastfeeding before going at it again. I just feel so depleted and need to feel like no one is physically depending on me.
Also I want to go back to work to start saving more and put extra money in super.
This all means that we'll end up with a 2.5 yrs gap. Same than we have between #1 and #2 which worked great. Only one in nappy and enough understanding to be able to help with the baby etc.
I don't think age gaps matter too much regarding close relationships between siblings. It's a matter of personality IMO.