I'm worried about my lips. I want to get fillers.

I buy products to copy the pretty lip makeup looks I see on YouTube, but it stresses me out because the vibe doesn't come through at all when I actually apply them to my lips. My upper lip is as thin as paper, and when I'm not doing anything, the corners of my mouth droop downwards, so people around me ask me all the time, "Are you angry? Are you in a bad mood?" Even when I try hard to extend my lips with an over-lip pencil, only the outer edges remain after eating, making it look hideous. I feel like I just need to restore some fundamental dimension, so I'm looking into lip fillers. I want a lip design where the volume fills in dewily while the corners just snap up, but I'm hesitating to buy it because I'm worried it might end up looking like the overly exaggerated "Gangnam Unnie" style duck lips. If I get lip fillers, does it feel hard and lumpy when I kiss or eat? I've heard that lips have a lot of blood vessels and it really hurts; please tell me honestly if it's bearable even with anesthesia.