it's common and heard from sono and doc usually it will move up on it own.. many mummies, including myself had it during 1st trimester and lasted until week 28 or even week 30+ for some.. just try to rest as much as you can, avoid carrying heavy stuff (like more than 5kg), avoid intercourse..
I found out about low placenta when i had heavy bleeding at 14+ weeks. Was on bed rest for a week & since then gyane advised to avoid sex & any strenous activity. It was still low around 1.2mm from cervix at 21+ weeks.
Same for me. Went up at 24/28 week. can’t remember. should be ok