Mustafa, my apologies for the delayed response! I've been thinking about your dilemma and this is what I've come up with. I'd make the most of the vertical space in the room so that you allow yourself maximum square footage for counter work space. If you're able to, I would suggest putting the refrigerator on the opposite wall (where the tall storage unit is in the sketch). Something similar to this:

A houzz contributor, not too long ago, had made a wine rack out of 4'x4' wooden pallets, that are used in the US to move a load of goods with a fork-lift truck. Perhaps they have them in your country. He cut them in half so they were only two feet deep and stacked them up to high counter height. The wood would be a nice contrast with your concrete, might add a little warmth to the space. cascio.offsite@gmail.com

One of my clients had no designated space for puja in their home, and they would have had to squeeze it into a passage somewhere. So when they came to me for ideas, I noticed in the floor plan that they had a beautiful covered verandah overlooking a private garden. The wall of that verandah was towards the east side of the garden. So I thought- why not carve out a rustic simple puja space here? Outdoors? The client was game. And this was the result- a 2'-0" x 2'-6" wood panelled niche in the wall, with a simple clay Krishna placed on a wooden bracket with a delicate hanging brass lamp

Just because you want to use the space below the stairs, do not just add drawers or shelfs unless you reaalllyyy need it. I would suggest go for adding something green to your house. Its healthy by adding air purifying plants. These plants are nowadays available in most of the nurseries and moreover Green patch in the house gives a beautiful look to the house and is also good for eyes ( the green color). Below are few picture to motivate you for Green patch or Indoor garden.