It looks like you've measured the 3mm from outside to outside of the pins. If so, then you need to measure middle to middle, of outside to inside. It looks like it's 2.5mm or (more likely) 2.54mm (0.1 inch). As requested, an end on picture will be more useful.
Looking at the first picture, the left hand edge of the left pin appears to coincide with 12mm, the right pin, 14mm. That gives a pitch of 2mm. Can you find anything similar on this page?
The very thin section and "winged" profile reminded me of some five way ones we used for something last year & I've just dug out the type number to find the two way equivalent.
I'd advise getting ones with wires fitted, as if you get the separate housing you have to also buy the crimp inserts. We got 100 just to make up two connectors with only two wires in each..
It looks like the two pin version is commonly used in models and they are readily available with pre-fitted wires, from such as Amazon and drone parts suppliers.