Topsoil is usually buffered to a lower ph, (6.0 or so) so I'd contact Scotts, and see what their Topsoil is buffered to.

Miracle Grow All Purpose directions are for a 10 to 14 day period. (1 tsp per gallon) Half strength (a weekly dose) would be approx 1/2 tsp per gallon. When I use it, I use 1/4 tsp per gallon, twice a week.

6.5 ph ingoing is a tad low before adding nutrients. Try bumping it up to 6.8 or 6.9ish before nutes. 6.5 ph is fine for plain waterings, though.

Too young for a true calcium or magnesium def. But unsulfured molasses at 1/4 tsp per gallon, once a week usually doesn't hurt, but is mostly unnecessary. In mid to late flower, I give 1 tsp per gallon, once a week.