My Brothers Dick

He is my brother from uncle, a we had normal familiar relationship until one day
He was in my room and i needed to go out, by walking by him i touched his legs with my butt, at first i didnt realised but i thought he had something in his pocket and walked away.
When i came back to room, he was there sitting on his phone, i sat next to him and put my legs on his legs. I think one minute was to much, something started to touch my feets, i moved my legs a little bit to put that thing away, i zhought it was his wallet or something, and i realised it was his dick. From my legs movement it gets hard, and what i felt on my legs it was heavy.
He did not reacted, and i puted my legs away after few minutes.
My boyfriend is about 13cm long, and i think from what i saw on my brothers shorts that he is above average, minimum 20 cm, i never saw dick that big.
From that day, i think about that shape on his shorts, it was so hard, i thought it would jump from his shorts.
I love my boyfriend and we have good sex, but i would like to just see what my brothers big dick looks like, i am so shy to ask him