Moms that have given birth -what do contractions feel like?

Mariah • Baby #4 :)
What do contractions feel like? I'm so confused because my OB told me that the "period-like" cramps I was having along with the sharp vaginal pain this past weekend were contractions, but they weren't labor. She said when they are regular and can time them 4-1-1 then go to the hospital bc you are in labor. 
What do contractions feel like when you are about to go into labor? Do they start off feeling like period cramps and just keep getting worse? I wouldn't be able to time what I had this past weekend... Help?