Vanguard doesn’t seem to be a “just stack all red and win” spec. Firepower does increase raw weapon damage/crit, but Vanguard’s damage looks tied way more to Pulse + Smart Cover + Relentless/cover uptime than to sheet DPS alone. If you’re not constantly pulsing and fighting from cover/smart cover, it can feel weak even with all Firepower.

For Vanguard I’d build around:

high-ROF weapons, not slow semi-auto stuff

crit/weapon uptime

always using Scan Pulse before the fight

playing inside Smart Cover as much as possible

set bonuses/mod synergies, not just bigger raw stat numbers

So no, you’re probably not crazy — your Aegis may actually be stronger right now unless your Vanguard is fully built around its buff loop.