When working out the hits from a suit of armour, you add up the (minimum) coverage and go for the lowest. This is usually but not always the torso piece…
Harry the Marcher: Steel breastplate (but not backplate), padded leather on both arms and both legs. Suit is light armour, +2 hits, with a bit of CLEAVE and IMPALE immunity on his chest. Because he isn’t wearing enough heavy on his chest to count 1 location, let alone 2.
Argent the Dawnish knight: Aluminium scale armour (medium) on whole of torso, heavy leather helm (medium), plate greaves and vambraces (1/2 arms + 1/2 legs, heavy). 2 locations covered, but only enough armour for a medium suit (+3) with a lot of CLEAVE immunity but IMPALE immunity only on the greaves and vambraces.
Petrius the League Pikeman: Steel curiass (breastplate and backplate, heavy), left arm and leg in plate armour (steel, heavy), right arm and leg in padded leather (light) and a fancy hat with a feather in it. Because he fights in a side-on stance, that’s why. Torso and 1 location (1/2 legs + 1/2 arms) in heavy, rest in light. He gets +4 from the heavy and CLEAVE and IMPALE immunities on his torso, left leg and left arm. He hopes no-one gets behind him.
Your example is accurate, steel breastplate (heavy but only on front), thick leather (medium, depending) on say the rest of your torso, head and legs… medium armour suit (+3 hits) immunity to CLEAVE (on the armour) and IMPALE (but only on the breastplate). It’s a pretty good set.
Note that CLEAVE and IMPALE hits still do 1 hit, you just ignore the extra effect. A guy (2 hits) in full plate armour (+4 hits) should fall if you hit him 6 times with arrows.