You have accomplished a lot. Ridding 50#'s is no easy feat. You have lots to be proud of.
The key to success is doing whats important or what feels right to you... accomplishing that goal... and moving on to the next goal... and accomplishing that one, etc. etc. etc.
What I would do for your current goal is get yourself a journal for this next phase. Write down your goals and your measurments along with body fat. Yoiu may even want to take pictures. Take note of the type of eating schedule it took for you to lose weight. For instance did you follow a low carb? If so then for the building mass stage do opposite, for instance, and do high carbs. And then increase your caloric intake by about 500 calories a day or you may consider staggering your intake for instance 250 calories one day, 0 one day, 500 calories one day, 700 calories another, etc.
Eat healthy, nutritious foods. Record the changes in your physique weekly to learn whether or not the changes you are making today are bringing you closer to your goals tomorrow.
Be happy. Keep up the good work. You are doing great!!