No supplement is worth the money. Just stick to your eating plan and exercise-it will happen. 30 pounds in 4 months is just awesome-but after a huge initial weight loss like that-it will naturally slow down as you get closer to your goal weight. This is normal and you are not doing anything wrong. The old saying "the last 10 are the hardest to lose" is totally true.
The best way I have found to get through a plateau/slow period is to shake up your exercise. I keep my workouts varied. I am a belly dancer and have rehearsal and technique 2x a week...and I also do Pilates and strength training, and walking on other days of the week. My body never knows what is coming next!
You are doing fine...just expect to lose a little slower now that you are closer to goal.