Extending a baby blanket pattern

I’m knitting a baby afghan blanket from a free online pattern. I realized once I was into to the blanket that it was too small. So I decided to added a border in the same pattern - it’s multiples of 10 for the pattern plus 3 border stitches on each side. I have done the top & bottom by trial and error. I have taken out the knitted border several times because I don’t know how to figure out how many stitches I need to pick up. Anyone can give me advice on picking up the right number of stitches? My friend’s baby is due soon! Thank you!

Generally you pick up one stitch for every row, but it can vary based on pattern. If you can give us the link to the pattern it would help.

thanks you so much for hte quick reply. I am attaching the doc file for the blanket instructions. I’m not using two strands of they suggest and that’s probably why it’s too small. I started to extend the blanket with:
knit 4 rows, pattern 10 rows, knit 4 rows. bind off

On one end I picked up 129 stitches and on the other end I have 140 (I think). So one end is now bigger that the other & I don’t know which one to rip out since I can’t figure out how it will block. Arg!

Of course, I don’t want to start on the two long sides of the blanket until I have figured out how many stitches I need to pick up. I’m attaching a .doc of the instructions. The pattern is soft as a cloud from freepattern.com – I didn’t know how to link you to that site. (So much to learn, so little time.)

You folks rock! I’ve been using the video demos to figure out all of my other problems.