re: How to break through a running plateau

So a few things:

1. 3 months is nothing in the grand scheme of running. A lot of the people you see posting great times have years of lifetime miles built up. You'll see progress as you keep doing what you're doing

2. You need to add more mileage. The rule of thumb is 10% increase per week, with the 4th week being kind of a de-load week. I'd gradually add distance to those easy runs and the long run while keeping your speed work the same and see how your body reacts to that

As far as your last paragraph, I'd need more info. What do you feel like is holding you back from running something faster? Leg fatigue, inadequate cardio, etc?