Offlane is so stupidly simple below 3k
Literally all you have to do to rank up is learn how to not miss a creep wave. Understand when the enemy support is pulling and contest their pull. Do not let their support harass you for free. Use spells to contest range creeps. Build for lane sustain and get your important item timings like blink + bkb etc then 60% of your games will be winnable. Fight around whichever teammate has the longest ult cool down and disrupt the enemy supports.. Farm when the fight is over. Rinse and repeat until you have finally pushed in to their ancients.