Help! My progect is mutating!

[tasty_graffiti]

I am working on a crocheting a shirt

link: http://www.naturallycaron.com/projects/rosario/rosario_4.html

but as I am working my project is growing!  It started out as 18 inches long but now is to the size of 25 inches!  I am not adding stitches, I don't know what to do!  It doesn't feel like my crocheting is becoming more relaxed, I'm not sure what to do.  Help me please!!

[tasty_graffiti]

Here is an image of the project ^_^

[rmpbklyn]

that last chain is the step stitch  but not a stitch to consider for length
if you need 10 stitches , then do 10+1 chain stitch at the end of row

add markers by a contrasting yarn like red or yellow that can pulled out later, say for every 20 stitches ,it's easier to recount to keep track

[kirsa]

It looks to me like your starting chain was probably just too tight.  It's a problem that I have pretty much all the time, where my starting chain is considerably tighter than the rest of my stitches.  I've found it helps to go up a hook size (or sometimes 2!) for the starting chain.

[tasty_graffiti]

Genius!  Thank you so much for you help.

T_T not an easy fix though for this project... But I'll know for the future!