12 weeks and everything exhausts me

I’m 12 weeks with my second child. My body is so tired. I went to the grocery store for about a hour tonight and after I felt like I just ran a marathon. Anyone else feel like this? I don’t remember feeling this out of shape the first time around 3 years ago. I was working on my feet all day then. I now work from home. My knees, feet and back ache after standing or walking for a period of time. I ordered a belly band to see if that would help with support. Anybody else feeling like this ??