Loop compensation design of buck converter
Your approach looks sound from a theoretical perspective. From a practical perspective, the exact phase margin point isn't a concern so long as you have -10dB (or less) gain. Your gain line looks fine to me.

Your simulated results are going to be somewhat different from reality even if your components match the values you chose, as parasitics and other delays not considered by your model will affect the overall loop response. That being said, this sort of theoretical computation is generally the first step in designing a stable compensation network. The subsequent steps, of course, would be:


Build the physical circuit
Measure the plant and overall loop responses
Adjust and remeasure the compensation as required