Am I too big for my age and height?

Ok, so about a year ago I was obese. I was almost 14, 5 foot 4 and 178 pounds. I decided to change my lifestyle. Now I am 14 almost 15 and about two months ago I was 5 foot 6 and 122 pounds and I was so proud of myself. Then last week I weighed myself and I was 139 pounds. I was not very happy, so I lengthened my exercises a little and ate even healthier. Today, I weighed myself and I an 144 pounds so I gained 5 pounds in just one week!! When I pit on my favorite pair of jeans, I had to squease into them and they gave me a muffin top. I also noticed some new, squishy flab around my belly :( am I too big? What can I do to get back to 122 pounds by July-ish?? Thanks :)