Brief Answer:
N.A.D means No Abnormality Detected.
Detailed Answer:
Hello Mrs XXXXXXX 
Thanks for posting your question.
Your 
ultrasound finding means you do not have any problem.
NAD stands for No Abnormality Detected. So relax, there is nothing wrong with you.
As for the bladder being hyperdistended, before doing the scan, they would have told you to drink a lot of water, and hold back the urine, the bladder gets distended if you hold back the urine.
This is done to make sure that 
uterus and ovaries can be seen easily in the scan.
So your ultrasound scan is fine.
As for missed periods, it can happen once in a while, you don't need to worry too much about it. You have mentioned that you have not got your periods for 5 weeks now, I would like you to wait for another two weeks and then repeat the 
pregnancy test, some times the 
pregnancy tests become positive as late as 45 days after conception, that is about 2 months of missing periods.
Do not panic, do the test again after two weeks and see if you are pregnant, if that also comes negative, then you can be sure that you are not pregnant.
Hope this answers your question, if you have any doubts, please write back to me.
Wishing you good health.
Regards