Mommy burnout?

Has anyone experienced this? I've been lucky and have been able to be a SAHM since my son was born, he's almost 16 months. I'm grateful for being able to stay home, however I'm noticing I'm starting to burnout.

I find it's usually at the end of my husband's work week where I know I have his help for the next couple days so all my energy is just deflated by the end of the week.

I start to notice the burnout when I don't have the energy to entertain my son all day and be "on" and super happy. On these days I get short, quiet and want to be by myself which also shows that I probably need a break.

I feel guilty because today wasn't a great day but it wasn't a super bad day, just very boring and you could tell my son was fussy and bored. I feel like a bad mom.