What spell slot count formula can I use to base my homebrew

When a spellcaster casts a spell using a slot that is of a higher level than the spell, the spell assumes the higher level for that casting For instance

You get ONE 10th level spell slot Period You never gain an additional 10th level spell slot under any circumstance or by any means other than the appropriate

spell slot Added one extra spell slot to characters at the start of the game for a maximum of 14 This is the maximum number of spell slots the game supports

spell slot tracker Most levels that see an increase in spell slots give you about levels of spells per level Levels 1, 3, 5, and 9 give you more Levels 12,