Dear thanks for the question. 
I share your concerns as you are trying to lose weight but not able to succeed. Firstly I would like to tell you that have confidence in your self,  because it is achievable. I must inform you that efforts you are putting in are not enough,  you need to work much harder. 
I would suggest following to my patients
     1  walking/jogging for 3 to 4 miles every day (start with 1/2mile)
     2  exercises in morning and evening (total 2 hours a day other than walking)
     3  strict 
diet plan (absolute no to oil, butter, cheese, egg yellow, boiled vegetables, reduced cereal intake. 
 This approach you need to follow for 3 months as you have to lose 45 pounds. 
If this approach fails I do tests on my patients like 
thyroid,  sugar, blood work up, hormone studies. Last resort is to under go weight reduction surgeries. 
I hope i have clarified your queries. Do write for follow up queries. Please rate my reply. I wish you good luck,  you can do it. Thank you.