Google Sheets - Combine multiple IF Functions into one cell

I'm trying to produce a SKU in Google Sheets for a product using the values of three variants (Title, Colour and Size)

The product is 'Lightweight trainers' with colour variants of 'Red' and 'Blue', and the sizes range from 5 - 12.

Link to spreadsheet

https://docs.google.com/spreadsheets/d/1trq0X3MjR-n2THFnT8gYYlwKscnQavCeeZ8L-ifYaHw/edit?usp=sharing

Aim

I'm hoping to have a SKU that displays the product, the colour variant and the shoes size. Example: LW-1-8 (Lightweight trainer, colour Red, size 8)

Product is Lightweight Trainers with a value of LW.

Colour variant 'Red' with a value of 1 and 'Blue' with a value of 2.

Shoe size variant = number ranging from 5 to 12.

Here's what I have so far, joining the colour and size variants.

=IFS(I2="Red",1,I2="Blue",2)&"-"& IFS(K2="5",5,K2="6",6,K2="7",7,K2="8",8,K2="9",9,K2="10",10,K2="11",11,K2="12",12)

However, I'm getting stuck in joining the data in column B with this function.

Any help with combining this data from multiple cells into one would be greatly appreciated.