To the OP: A good way to increase your pull-ups is to change the way you train a bit.
Try this out to up your up your count.
Do this set twice through:
1 pullup.. drop, wait 15 seconds
2 pullups.. drop, wait 15 seconds
3 pullups.. drop, wait 15 seconds.
4 pullups.. drop, wait 30 seconds.
5 pullups.. drop, wait 30 seconds.
4 pullups.. drop, wait 15 seconds.
3 pullups..drop, wait 15 seconds.
2 pullups.. drop, wait 15 seconds.
1 pullup.. drop
This builds up great upper body strength and endurance and is a lot tougher than it looks, especially once you start tweaking the numbers when you can do more. I used this training method and I can bang out around 25 solid ones, (gets a little ugly after 20). Once you start feeling good at it, go for 18 in a row.