First time

So, I had my first session. Showered, cleaned, lubed, ready to go.
I initially inserted it while laying on my side, then i turned onto my back laying normally. I started doing some deep breathing while contracting, as if when i breathed in, i contracted. They were intermediate contractions, nothing small or big. After about 30 minutes, I think I had my first p-wave.
It didn't feel like any orgasm, but it definitely felt like a wave. A strange feeling occured during it; As I felt my heartbeat, it felt as if the beat was going up and down my back, it was… very strange, to say the least. Such as they are.