I have to agree with Sandy, there are no quick fixes to achieving breast growth. I have been on HRT for two years, and still am not satisfied with my own growth. Genetics play a huge role in this process, and it all depends on how gg women in your family developed, but even then that is only a benchmark, and not an accurate representation of how you will develop.
Give it time hun. When you went off the hormones to donate sperm, your estrogen levels probably dropped, so it's probable that no development was taking place during that time. It will take a few weeks to months for your body to start up again, and getting used to having the hormones back in your system.
Even in gg women, breast growth does fluctuate depending on where they are in their cycle, and also during and after pregnancy (which doesn't apply here, just saying).