4 is great!! I'm doing pullups/ chinups now and a year ago I could seriously NOT lift myself an inch. I started doing negatives, which is basically using a chair to assist myself over the bar & then SLOWLY (at least a 4 count) lowering myself back down. I would do as many as I could. And now I do *pulse-ups* which is basically when you get back all the way down, then do kind of a very slight movement up (kind of like Cathe's low-ends }( ) until I can't do anymore. There are different variations- wide grip, close grip, switch grip, chinup, etc.
Just keep at it, most women can't do 1 so you're way ahead of the game! HTH!