It's not just protein intake that counts, it's total caloric intake on a consistant basis. You're guessing you're taking in 3500 cals. Most of the time when people guess what thier caloric intake is their about 1000 short. I've seen it happen all too often.
..........until I did my first cycle and started writting everything down I was amazed at how far off my guessing was. I was only taking in 3,000 on that cycle.............I weighrd 171 and gained 20 kept around 14