Hello ,
Basicaly you are aiming to loose some weight. But the problem you shared of breathing while regular activity and taking stair case need to diagnosed first as if it is only due to weight factort or any other cause.
Next Steps
Kindly check your blood pressure ,
Lipid profile levels, haemohlibins and ECG (if required)
Health Tips
Continue with simple exercises like walk ,
Please try to get personal medical advise as early as possible for blood pressure and above mentioned inveatigation nearby .Consult directly after above things done if required