@ Reaghan - That sharp pain you described sounds like ligament pains. We used to have patients come in all the time with those, mistaking them for some signs of labor. Ligament pains consist more of a sharp, shooting pain, one side or both, radiating up the sides of your abdomen, they can be short and stabbing, or prolonged. Generally movement and gravity makes it a lot worse. The ligaments that support your womb wrap around from your back, down to the lower part of your uterus. Could be your bladder was full, which was putting more pressure on the womb, and hence the ligaments. Another thing could be (although unlikely) a kidney stone, which was lodged somewhere until you went to the bathroom. Kidney stones are pretty common in pregnancy, but there's no treatment but to pass them. Either one would explain why you had sudden relief when you voided.
Contractions, on the other hand and cramping, menstrual or diarrhea-like pains in the lower abdomen (sometimes in low back as well), lasting 50-90 seconds, they are gradual (increasing in strength until they peak), then gradually go away. The top of your tummy should get really hard with the contractions, again peaking and then slowly getting softer. Contractions that should concern you are ones that are regular, every 5-7 minutes (or less) for 1-1.5hrs, from the start of one to the start of the next, or if there's any bleeding, leaking of fluid, or decreased baby movement.
Hope this helps!
@ Lanespoli - Good for you!