Problem with clover and shamrock

I’m having a lot of trouble trying to establish my lawn its been planted three years now and has never really taken off. I have given it fertilizer twice this year (once weed and feed) but all I seem to be able to grow are mass bunches of clover and what appears to be shamrock with a yellow flower. What could be the problem. The lawn itself is very patchy and plants don’t seem to grow just germinate.