I've only been seeded by two men, but there's lots of feelings. I think the big one is feeling completely submissive to Him, but there's also the physical sensations, which are amazing. My first Daddy deflowered me and seeded me in the same session so I was really filled with emotions from my emasculation. When He seeded me, I remember feeling Him get SUPER hard inside my new sissy pussy and feeling His cock pulsating deep inside me up near my belly button. It felt suddenly really wet in my pussy like I'd been re-lubed, but I knew it was His seed coating my pussy. I remember reflexively squeezing my pussy muscles around His cock for a bit and He thought it was amusing that my new pussy was milking as much of His seed as possible.
When He withdrew, my pussy felt very different. She was pulsing with pleasure. Even for the next few days, my pussy knew she had been fucked because I could still feel the fucking she had taken. I didn't know that my pussy would leak cum like a girl pussy does when it's seeded, but when I stood up after, I could feel His warm cum leaking onto my stocking top. Daddy saw this and told me to get back on the bed for my plug so His seed would stay in me. I obeyed Him immediately! It was the strangest thing. Just completely submissive right away, I got on the bed, displayed my pussy to Him and He plugged me.