Slipping stitches purlwise - doing it wrong?

Hi all,

I’m new to this forum and I have an urgent question!
I started knitting again after years, so maybe I’m doing something dumb here, but somehow, I cannot get it right…

i’m knitting a straight 57 stitches piece to make a hood of it with the following pattern:
row1 WS: Sl1, K3, purl to last 4, K4
row2 RS: Sl1, knit to end

I’m having troubles with the slipping purlwise. I somehow manage to add stitches in to progress and that it not intended to be so…
I just put to right needle purlwise in the first stitch on the left needle, keeping to yarn on the front and slip it to the right needle. then I knit 3 more and so on… But every row I knit adds one stitch.
Am I doing something wrong?

thanks for the help!
Evelien (Belgium)

After you slip the stitch, check that you are bringing the yarn to the back for the knit sts by passing it between the needles and not over the needle. This will create a yarn over and look like an extra stitch. Also, make sure that the yarn in front is pulling down and that you are not somehow pulling up on that yarn so that the last stitch from the previous row looks like two.
You can tie a small piece of yarn around the needle after the first 4 sts and before the last 4 which will act as a stitch marker. Be sure that when you finish the 4 end sts that are forming the garter stitch trim, you actually have only 4sts.

Thanks! I indeed forgot to swith the yarn any time I switched between purl and knitting.

Thanks for your help!!