Kids have no filter, you know that, but I doubt the child was bothered by you only having one bathroom.
Your house sounds lovely. Many of those in more expensive places will have been in far less earlier on.
Children just want to have a good time, for their environment to be free and easy. Relax and enjoy it, you have it for many years to come.
Looking back, I daresay we were a bit downmarket compared to some :-). We also only had one bathroom (but we did have a downstairs 'cloakroom'). We were also often in quite a mess. However children loved being at our house and we had many stay over, one virtually moved in at weekends and during the holidays. We were laid back and the kids enjoyed themselves. Some of the parents had second homes and went on expensive holidays, it made no difference.
My only child is now nearly 46 and still has many of the same friends; a lot came to his dad's funeral (& some of their parents), so it couldn't have been too bad :-). My child has now bought the house and lives there so it continues.......
You'll be fine. Think about it, you are being a bit snobbish. I know you don't mean to be but you are. It's you that matters, not your house - which sounds pretty good anyway.