Clearly, not Cathe here. And PLEASE don't take offense to this Eunice, but I absolutley detest it when people start to work out and their weight goes up and the reason always given is muscle weighs more that fat. I would LOVE to gain tons of muscle - do you know how long and how heavy we, esp as women have to lift to put on even 2 pounds of muscle? Likely a LOT more than most of us do with Cathe's at-home workouts, esp in one month. I always tell the ladies at my gym that that is NOT a reason. 5# of muscle weighs the same as 5# of fat, it just takes up less space. So in this short amount of time you would probably not gain weight AND have looser fitting clothes unless you went really heavy and really intense.
But Crash to be honest, I think you'd probably have to give Cathe a lot more info for her to base an answer on. What kind of diet WERE you eating and for how long. And in this last month have you gone totally clean all at once? How many calories are you getting now compared to what you took in before you started working out? The hour and a half a day, 6x week - how much cardio and at what intensity? How much were you working out before this? What kind of weights, a split or full body, and how heavy with how much rest. What kind of supplements if any do you take? How old are you and do you have any other physical factors that may affect weight, lean body mass, etc. What is the timing of your nutrients and what are your macronutrient ratios? You say a lot more protein and veggies - how much and what kind of protien and what kind of veggies?
I know that's not answering your question, but there are SO many variables to be considered, esp over the course of only one month. I just don't think saying if you are now using weights that you are likely gaining muscle is realistic. It takes many women YEARS of training and food journaling to be able to gain muscle. So again, I apologize to Eunice. But it seems that more info has to be considered.