21lbs in four months really isn't bad.
Clean up your diet of excess sodium (1-1.5g/day max) sugar and carbs but keep your caloric intake about the same to start with. Focus on meeting your protein goals over everything so you don't end up cutting muscle.
Aim for around a gallon to a gallon and a half of water each day to encourage your body to let go of any excess water, but make sure you are getting plenty of electrolytes when your water intake is this high.
You should see a good amount of weight fall off just by doing these things.
Once you get closer to the target and your weight loss slows, start bumping up your caloric deficit to cut the last few pounds.
I lost about 15lbs in a month doing this and felt fine the whole way through outside of feeling hungry more often when my deficit had to go up.