Is it possible to shed 20lbs in 3 months?

I am 145lbs – I wish to be 125lb by christmas -I’ve battled with this goal for a long while and I’m running low on time. is there any key tricks to stick too? other than the “put down the fork method” – I am a mom and its mostly tummy stuff and I have lower back problems that prevent me from impact excercises suchs as running – speed walking etc.. any and all advice/answers are welcome.