Playing against resourceless champions
I'd like some help with playing against resourceless champions mid.
I have always liked Leblanc, I won't say I have ever been GOOD at her but I like her anyway. Common foe I come up against are Katarinas, Yasuos, Zed, Akali and Rivens (sometimes)
I always come to lane with D-ring two pots, when I go crystal flask I feel like I don't have enough damage to do anything.
Katarina comes to lane with boots 4 pots, I try to push her out of lane but she just pops another potion and continues chipping at me with Q until I am out of potions. This continues until I am either OOM or well dead. When I ask my friends what I do about it they just hiss "MANAGE UR MANA BETTER!" at me... but I HAVE to attack her right? please help. I am tired of getting rekt.