Awkward First Time 😳

I am 20 years old and tonight a boy I have liked for a while asked if I wanted to “Netflix & Chill” for real. I agreed and it was so nice. He asked if I would be comfortable going all the way. I said yes but I couldn’t get him inside. I guess my body couldn’t take it yet. He is average size for a man but he was pretty thick. Any tips on how to prepare myself for next time, he ended up not getting it inside but I am embarrassed and feel bad.