With DC1 I was a stay at home mum. With DC2 I studied and did voluntary work, part time. With DC3 I work full time.
For ME, the toddler years are the best, and I would work part time again if I could. I think I enjoyed the freedom of not being tied to a school day, you can just pop out on an adventure whenever. But that's me.
I can't go part time coz DH fucked off and I need to put food on the table, so I'm not going to feel guilty about it. And neither should you.
My sister is a single parent to a 2 year old. She works full time. She felt terribly guilty and like she was missing out. She rearranged her hours so she now does them across 3.5 days instead of 5. Now she's feel guilty for missing bedtime, and Mondays at work.
You'll always feel guilty because we've been told we can have it all, but we can't. I've done the maths. There aren't enough hours in the week for me to have a career, be the mum I want to be, have an active social life, have hobbies and exercise, cook from scratch, maintain an award winning garden, support my parents and learn a new language.