Congrats on being 34 weeks na! Honestly, posterior placenta is actually one of the better positions kaya don't stress too much, it's not uncommon and usually walang problema. The "prematurely aged" part is what your OB needs to explain properly next week kasi that's the one you want clarity on, pero marami ring healthy pregnancies pa rin kahit may ganyan, so fingers crossed for you! I know waiting is the hardest part, pero isang linggo lang and you'll have peace of mind na from your doctor mismo. Rooting for you!