Help with a pattern

I am struggling with the following pattern instructions. “k3tog and leave sts on needle, yo, k3tog into same sts”. I have been knitting 3tog (so this k3tog stitch moves to my right hand needle), then I yo and knit 3 more together (so this k3tog stitch moves to my right hand needle as well). Is this correct? Some of my stitches are looking quite stretched and the body seems to be getting smaller than I think it should.
Also, not sure how to slip 1 WYIF at the end of a row.
Any help would be appreciated!
Thanks.

Welcome!
It sounds like you should be working all these sts into the [I]same[/I] group of 3 sts. K3tog but don’t drop the stitches from the left hand needle, yo, and then knit into the same 3sts again. Then drop the stitches from the left needle. You won’t decrease any sts this way. You’ll have 3 new loops over the right hand needle, 2sts and the yarn over.
It’s like this video:

For slip 1 WYIF, move the yarn to the front, slip one purlwise from the left to the right needle. Since you’re at the end of the row, turn, pick up the working yarn and proceed with the stitch pattern for the next row.

What are you making? Can you give us a pattern name or link to the pattern?

Thankyou for your reply! Here is a link to the pattern.
https://web.archive.org/web/20141021112614/http://www.petitepurls.com/Summer10/summer2010_p_yolanda.html

I’m still confused about sl1WYIF. I will have one stitch slipped onto my other needle, but it won’t be knit or purled in?

Move the yarn to the front of your work and slip the stitch without working it. Slip it from your left needle to your right needles.

I’ve figured it out!!! Thankyou both for your help👍

I’m at a new section in my pattern. Shaping the neck…See the following:
With RS facing, work across 25 sets. Join in new yarn and bind off 12 sets for front neck, work to end of row. (I have done this)
NOTE: Maintain daisy pattern while working decreases.

I am stuck on this next section.
Working each side with separate yarn, at each neck edge, bind off 3 sts once, then bind of 2 sts 2 times, then dec 1 ST at each neck edge every RS row 2 times (16 sts).
Work even until armholes measure 5.5 inches, put remaining sts onto stitch holder.

Thanks in advance🙂

The pattern is directing you to work each side of the neck with its own ball of yarn. You should be at the armhole edge of the right shoulder ready to turn and work back to the neck edge, drop the working yarn, pick up the first strand of yarn, bind off 3 sts and work to the end of row (the left armhole edge). Now turn and work across to the neck edge, drop the first strand, pick up the second strand, bind off 3sts and work to the end of row.
You’ll continue like this until you’ve completed all the decreases. For the decreases of one stitch you can do a k2tog and ssk one stitch in from the neck edge if you’d like.