In order to workout with maximal weight, 90-120 seconds is a good rest. However, if you want to maximize fat burning during your weight training, go for 60 seconds or less between sets. You won't be able to move as much weight but it comes down to what type of goals you have for yourself and from your comments it sounds like you are trying to lose some more weight.
BTW, congrats on the gains you have already made! You are doing great! Keep it up
