Miracle gro is not good for pot plants, it's too hot for seedlings anyways; as for transplanting you could transplant into the same size pot but it would be easier to go up a size. I would gently shake off the root ball to release the soil and place it in its new home; with fox farm.What would be the best way to transplant? I have fox farm ocean forest coming to me tomorrow. And am currently using miracle gro potting soil.
I grew my first try with miraclegro, its not the end of the world. You will end up with some good results in the end, minus being able to flush the nutrients so it might not taste the best.
Chin up.
You do however need better drainage. I strongly suggest you transplant it into a smart pot so that the roots can breathe. Do it ASAP, you are probably gonna end up with root rot otherwise.