I had a pelvic ultrasound at 5 weeks 5 days pregnant. the fetal pole compared to others i've seen looks abnormal to me. could it be a blighted ovum?

Not likely: An intrauterine embryonic pole at 5weeks 5 days is usually a reassuring sign particularly if cardiac activity was also detected and you have no pain, no bleeding..."Blighted ovum" is an unclear and obsolete terminology which is not very meaningful and is rarely used nowadays. Repeating your ultrasound in 7 to 10 days may provide you more reassurance.