At what point do you give a suppository?

My 9 month old hasn’t had a proper poop since January. For weeks now she’s just been pooping little pieces through the day. She hasn’t acted uncomfortable until yesterday when she pooped some bigger hard pieces (sorry) and it hurt her 😰 I was hopeful that cleared her out and that she’d start pooping more normally again but today another dry ball...

I went through this with my first. She ate a very healthy non constipating diet and drank enough but nothing I tried ever helped. Thankfully she just grew out of it. But I used to have to give her those liquid Children’s suppositories and to this day I still feel like I’m not sure when I should do it. Probably because I dread doing it so much and question myself

Advice?

Her Dr knows. Says “try peaches”