If it is a semi permanent (no peroxide) you can get a longer lasting colour simply by leaving it in way longer than the instructions, some people leave the high pigment semi permanents like Manic Panic in overnight.
2a-2c, medium texture, porous/ colour treated. Three years CG, growing out mechanical and chemical damage = breakage and very high porosity. Past armpit length heading for waist.
Treatments: Komaza protein, Komaza Matani, coconut oil with sugar syrup. Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss ultimate volume
Styler: Umberto Giannini jelly, Boots curl creme, Rockin RInglets
Experimenting with: Mega-Tek, Curl Harmony reviver, Elvive Full Restore 5.