Hi Jas, it is really hard to compare to anything. I guess period pain is the obvious one. That's not the most accurate for me because my period pain is easily controlled and frankly not very painful! Contractions were just more intense, I suppose and they didn't let up for very long, and they got more and more intense as they went on.
As for the pushing, wow, that was an amazing feeling. My second stage seemed to go on and on... It was really emotionally charged. In the lead up, I couldn't help pushing during most of the contractions - the urge was really strong. Pushing felt good because it was something I could consciously do - I didn't have to just breathe and wait it out. Then the stretch of the perenium during crowning is really amazing too. I felt the burn of it everywhere, but it was so fascinating - I don't think I registered that as pain.
All the best for your labour and birth. For a drug-free one, I'd recommend having yourself some really good, strong support.