Painting wooden stairs

[Imlostwithoutahope]

Help!
I had pine open tread stairs which were darkening our room so decided to paint them. I followed all the instructions and sanded, white spirit, primed, primed again and under coated twice. I then painted them with 2 coats of dulux timeless in satinwood. However the coverage hasn't been very good and now three months later the paint is wearing off.
Any recommendations on what else I could do ie what paint I can use for it to be long lasting/wearable.

Gloss?

Is it painted where you walk? You might find it better to have a runner in the middle?

Yacht paint? Or paint and varnish? Ours were painted by the previous occupants and varnished. I revarnished about 10 years ago and haven't felt the need to revarnish since.

Not good, did the varnish give a yellowy colour to the paint underneath?

We can't carpet them as they're open which means we would have to have the naf wrap around carpet on each tread. The alternative is to box them in and carpet but its £'s

Can't tell as the paint is yellow!

Actually it may not have been yacht varnish, might have been Ronseal Diamond Hard varnish - I see they also do a floor paint. Might be worth trying?

Sorry, getting confused there, thought I'd said I'd used yacht varnish.

I painted my stairs a year and a half ago with Farrow & Ball floor paint in a white shade - Wimborne white and they still look as good now as when first painted. Farrow & Ball is very pricey but they are good. I've used Ronseal, Dulux and Crown in the past and unfortunately they just don't give as good a finish.