Definitely stop with the Miracle grow nutes. Your seedlings don't need any nutes for the first 3-4 weeks in most cases. Also, should judge your watering based on the weight of the pot. No mattet what size pot I have a plant in I never water/feed more than every 3-5 days. Just because the top is dry doesn't mean it needs water. That could be due to the heat and airflow. Also, if you have a good quality soil, it's actually difficult to over water. You should be watering til you get some run off each time. At least enough to take measurements like PH and PPM.
Your plants don't necessarily looked nute burned. They could be in nute lock though due to the miracle grow feed. I think the first step is to check you water ph, then when they need water again, water and test the run off. If you can get a ppm meter that would be good too. Take note of how dark your run off is. You might need to flush them out, but check that stuff first.