Help needed..im so confused with the cal i need !!! Plzzzz

Hi,
I'm new at this and ive been working out for a while but havent seen a lot of results so i decided to log everything i eat.
I eat really healthy so that isnt a problem but im not sure im having enough cal in one day.
Im 27 years old femal 5 foot 135lbs and want to loose 15lbs at least. I have a muscular upper body but my lower is more fatty. I want to loose weight but dont really want to loose my arms and my 6 packs( its starting to show !!).
Im confused about the NET calories and excercising and all that..like do i eat back the cal i lost while exercising ?
Is there a way to calculate it without having to substract the working out cal cuz i dont really know how much cal i burn while weight lifting..the cardio part is easy but not the weight!!!
And how do i do my macro ? I know everyone is different but its hard to know where to start !
Im a nurse in an OR so im not sitted all day long, so im not sedentary and i work out minimum 4 times a week.
Thank for the time
Julie