Hey am new here-Help with new exercise regime

Hello everyone,

Bear with me because I am new to all of this! I recently wanted to lose a bit of weight and tone up...

I have joined the gym and go about 3x a week where I do around 20-30 mins of cardio usually the cross trainer or the bikes! And the gym instructor suggested to use resistance training to help lose the fat which I do a series of for a good solid 20-25 mins. This is all well and good, but I haven't lose weight even though my trousers feel a bit looser...

I am also eating 1800-2100 cals in total on workout days and around 1200-1500 non work out.
So I assume I net about 1500 cals a day...The reason I upped it because I was literally so hungry come 10pm and I would go to bed with a rumbling stomach and just generally feeling miserable.. I was only netting about 1000.

Do you think this is a good strategy! Any help would be appreciated. And if am eating too much please let me know!