with chords like Fm, since your middle finger isnt being used, you can use it to "help" hold down your index finger for the bar.
with chords like C, instead of using your middle/ring/pinky to hold down the 2nd/3rd/4th strings, try making a "mini bar" with your middle finger to hold down all three strings, and use your middle finger to "help" hold down your intex finger for the bar.
for chords like F and Cm, i would, as rayan stated, try to position your index finger acting as a bar as close to the fret as possible. the closer you get to it, the less pressure needed to hold the strings down cleanly (is "cleanly" a word?).
rolling your finger may also be posing a problem. proper form will eventually pay off. just keep at it till the sound cleans up. then once have the finger dexterity, you can try the "lazy" way to make chords. kinda like eric clapton does every now and then. i always wondered why it sometimes looked like he was just laying is fingers on the fretboard aimlessly. then i looked closer and saw the method to his madness. if youre just strumming rhythms with a band, you dont always need every single string to ring out.