Most likely that MG soil had lots of time release feed in it. That's probably what saved your plant.
I don't think Scotts makes a soil product that doesn't advertise "extended release" or "feeds fo up to six months". (some of their products even have visible clear gelatinous balls in it)
They can work, but you have no control over what is being fed to your plants, nor do you know what was excluded, or included in that soil, so it is more dificult to diagnose when things go bad.
Since you haven't fed her at all, just feed her something not too strong. What brand is up to you. Since you are flowering, try an NPK around 2-6-4 every other watering for a couple weeks and then back it down some to around 1-3-2 till it finishes. This is safe and it should respond in a few days.
If you use MG nutes, you will have to do the math on the dilution. MG makes a product called "Bloom Booster" that has an NPK ratio of 15-30-15. It is lower on pottasium than blooming plants prefer, but you can use it.
For example: If the bottle says, 1 Tablespoon per gallon of water, you would achieve roughly 15-30-15 with this formula.
For example: If you wanted to get close to 3-6-3 you would divide that that number by 1/5.
There are three teaspoons in a Tablespoon, so a 1/2 a teaspoon would be a 1/6.
This would give you an NPK of 2.5 -5 -2.5.
I am not recommending any brand specifically, just explaining how you can use the products and adjust the NPK to suit your needs.
You can feed stronger, less frequently, but I like to apply nutes in lower more frequent doses.
