Yes you can make changes. I would definitely listen To Cassies words, she is talking a lot of sense
Your calories should be up around 2,000, and you should do stuff like HIIT, Interval etc etc, as walking on a treadmill at the same rate all the time, can become a lack of a challenge for ethe body after a while, because the body gets used to it.
High impact stuff, where the intensity fluctuates will work for you better.
Again as said, Weights would be beneficial, and Cardio need only be 2-3 30 minute sessions as described above, as too much Cardio with inadequate calories can be very Catabolic, which could reduce muscle mass, lower Metabolism, and contribute to more Fat gains.
Again with the diet, it's not about limiting yourself to low Carb, or Low Protein, or having a points system, or anything like that, it's about sensible manageable alterations, with sensible foods.
It will all take a bit of time and patience to get used to, but you should be able to settle into a new workout and eating regiem in about 2 weeks.