I finally did it.

After 10 months of being together and having sex, I finally managed to do something it was impossible with my 4'3 x 3'6 dick. I made her cum from PiV.

I was fucking her in a position similar to "The Captain", but I was holding her legs more up and closer to my face. After a while, I noticed she started to make that face when she is having extreme pleasure, and I continued until I was near busting. I stopped and asked her what happened. She had a shocked face and just nodded at me. I touched her pussy and she was really wet all around. She almost always squirt when she has orgasm, so I tasted my fingers, and it was indeed squirt. I asked if she came, and she said "yes". I was so happy, and she was happy too but also shocked, because she also believed it's impossible for her to cum from PiV. But here we were. Then I got back to fucking her in the same position, and she came again.

So if someone has a 3-4 inch dick, I definitely recommend The Captain position.