what product should i add to get a better skin?
I think you have a very solid routine, I'd only recommend to change the Martiderm serum to smth more potent. You could consider a retinoid, for example this one: https://whatsinmyjar.com/product/alastin-skincare-renewal-retinol (also contains niacinamide which is effective in reducing hyperpigmentation), or more affordable option: https://whatsinmyjar.com/product/innisfree-retinol-cica-moisture-recovery-serum.
When starting a retinoid, be careful to avoid exfoliation. Possibly skip it altogether for the first couple of weeks or reduce to once a week.