German Shepherd (intelligent pup with an overthinking owner)

Hello there! I have an 18 week old German shepherd and a lot of anxiety that comes with overthinking and questioning if I’m doing things right. I’ve gotten so much conflicting advice as to whether I should let strangers pet her or not. She does really well in public and will ignore people/walk past with me (although she does notice everyone she’ll look up to me and keep walking only rarely sitting down to watch them and needing a redirect) but at home she does a more stern bark at people walking by (if she’s late for a nap, she gets really upset and walks me to my coat like she wants me to take her outside to investigate/bark her head off at the passerby) We currently are enrolled in puppy classes and plan to move to protection/bite work eventually. I just wanted to ask, do I need to worry about socializing her as far as letting her say hello to strangers? Or should I focus on keeping her engaged with me and praising for sitting by me as they go past? Last question if you’ve made it this far in my ramble, she will only potty/poo in the backyard. She will hold it if we go to the nature center or a trail/walk until she gets back to the backyard. Thank you for letting me ask these questions, I’m determined to give this pup the best life possible, she’s so smart and wants to please me so bad. I don’t want to let her down.