Dreams involving body parts, especially significant ones like arms, often symbolize personal power, capability, and the ability to take action. In your dream, the act of cutting off your right arm—a symbol of action and productivity—could represent a desire to let go of something that may be limiting you or a part of your life that you feel you need to release. The fireworks could indicate a celebration or a transformative moment, suggesting that this release is viewed positively.

The fact that your arm grew back without blood or pain can symbolize resilience and the ability to recover from challenges. It might also reflect your feelings of support from your girlfriend and mutual friend, as they appear to be happy in this situation.

As a left-handed person, the right arm might also represent aspects of yourself that you are less comfortable with or that are less dominant in your life. This dream could encourage you to explore new possibilities and celebrate your ability to adapt and overcome obstacles.

Overall, this dream seems to suggest a journey of transformation and the importance of support from those around you in this process. Consider what aspects of your life you might be ready to release or change, and how you can celebrate your growth and resilience moving forward.