Best Recumbent Bike

Hi there ! i recently invested in a recumbent stationary bike. It does wonders! personally i love it better than a treadmill, it hurts my joints less and i can keep on going on it for longer than half an hour!
This has been my 3rd day now and each day i have been burning 500 calories in an hour of being on the bike. I want to lose 15-20 pounds, how long do you think it will take me if i keep this up 4 days a week? I also eat eggs, toast, bacon and some times hash browns for breakfast, lunch time i usually eat sushi or soup and dinner , chicken breast , veges, salads , fish , mashed potatoes or mini round potatoes. Is there anything you would suggest? I eat 3 times a day , it’s just how my body always is i have a really good metabolism , its just one year i went on a big splurg and now i have been the same weight for a year ever since! how many pounds do you think i will lose if i keep this up for a month or 2 weeks? Not sure how calories work and all. 3 days i work 12 hour shifts ( and im basically standing for 8 hours of it , not sure how many calories that will burned either! ) thanks so much for reading

I am 23 yrs of age
I am only 5ft 1 weigh 145 pounds ( i def don’t look it though, from what people have told me they are shocked to believe i am that weight, i look 130 pounds , which is really weird! i guess the fat is everywhere or in one certain spot)