Why is losing weight so hard 😩

I've had two babies and gained over 30 lbs in the last 5 years. I'm currently 5'2" and 138 lbs. I would like to be able to lose at least 20 lbs but need help! 😭 I went on a diet for 2 months and counted calories like crazy, I never let myself get over 1400 in a day. I didn't lose anything so now I'm really discouraged!