Hello Thanks for writing to us with your health concern. At 17 weeks and 6 days, you would definitely be showing. And at 18 weeks, a pregnancy cannot be cryptic by any means ! AN ultrasound would be most confirmatory. A quantitative blood test too would conclusively tell you if you are pregnant. Please schedule an appointment with a gynecologist. If a pregnancy is suspected an ultrasound would obviously be done. Do not delay this long. If you are not pregnant, a reason must be sought for not having had a period for almost 5 months now ! Rule out other conditions like hypothyroidism, polycystic ovarian disease, obesity or a hormonal imbalance. All the best and take care.