If you face the Catalan from a Queens Gambit Declined position , I admit to have the same problem. My antidote is the transposition to a Dutch stonewall defense. After his 3.g3 play 3...f5 and when you complete development follow the road Bd7-Be8-Bh5 and exchange your light square bishop with a knight.
It's not a instructive way to deal with the Catalan but if you are not ready to spent time understanding the theory then , the Stonewall it's a solution...and don't forget, Catalan players hate to see this!
I don't have much of a system to begin with as Black against D4, but when facing the Catalan, I just wanna cry, lol. I can never get my light squared bishop developed and my position just ends up collapsing, lol.