Heat 1 tablespoon olive oil in a large nonstick skillet over medium-high heat. Add the onion and cook, stirring occasionally, until slightly softened, about 5 minutes. Add the bell peppers and 1/2 teaspoon fajita seasoning. Cook, stirring occasionally, until the onion starts browning and the peppers are slightly softened, about 3 minutes. Add 1/4 cup water and continue cooking until the vegetables are tender, about 5 more minutes.
Meanwhile, whisk half of the lime juice with 1 1/2 tablespoons olive oil and the agave in a medium bowl. Add half of the cilantro, and the onion and peppers (reserve the skillet). Season with salt and pepper; toss to coat and set aside.
Wipe out the skillet and heat over high heat. Toss the shrimp with the remaining 1/2 tablespoon olive oil and 1/4 teaspoon fajita seasoning in a bowl. Add to the skillet and cook until the shrimp are pink, 2 to 3 minutes per side. Remove from the heat and add the remaining lime juice and cilantro; season with salt and pepper.
Warm the tortillas as the label directs. Divide the lettuce among bowls; top with the onion and peppers, shrimp and pico de gallo. Serve with the tortillas and lime wedges.