New here, wrestling with position sizing on $SPY swings

Hey everyone, been lurking for a bit, figured I'd finally jump in. Still fairly new to actively trading, mostly focused on intraday/swing setups on $SPY options. I'm getting a handle on identifying decent setups, but my biggest headache right now is consistently sizing my positions. I feel like I either go too small and the move isn't worth the screen time, or I go too big, get chopped, and take a disproportionately large hit. I've tried a fixed percentage of my account, but that feels too rigid for varying volatility. How do you guys adjust your position size for different market conditions or the perceived quality of a setup without overleveraging or being too conservative?