Haha welcome to the club! Mengeras tu memang macam perut jadi tight dan hard suddenly, kalau you pegang, rasa keras macam bola, bukan soft macam biasa. A few of us mum friends describe it like when the whole belly just contracts and feels super tense untuk a few seconds or minutes, then lepas. Kalau you rasa tegang je or occasional tightness without the hardness part, that's usually just normal stretching or Braxton Hicks yang mild lang. Tapi since you're worried, better check with your gynae next appointment to confirm semuanya okay, they can tell you exactly what's normal vs what to watch out for at 17 weeks!