Attempt at designing sweater for the first time

So my friend sent me this picture in the beginning of winter..

and I instantly fell in love with it!

I tried to find a pattern that looks similar, but to no avail. Berroco, Lion Brand, Ravelry, all failed.

So I finally decided to design my first sweater. It's going to look very similar to that, except it might not become a jacket, unless I master steeking (!). Does anyone recommend a good steeking tutorial video?

Since it's my firest design, I'm going to try to destash as well.

Yarn: RH SS Purple and Light Grey (I'm starting with 1 skein each)

Needle: US 8 (5mm)

Other materials: 4+ stitch markers, cable needle.