Labioplasty works the best for a labial reduction. However it entails surgery. ThermiVa works best on tightening the labia majora but has some affect on the labia minora and with the enhanced sensitivity in the clitoral area the overall benefit is excellent. Plus no down time.
The symptom that caught my attention was the chronicity of your itching (all your life)). Certainly skin on skin rubbing with the addition of heat and moisture from your clothing can cause itching at that site. There are skin conditions that can occur at an early age that can give you vulva itching. For accurate diagnosis a vulva biopsy may be required. With use of technology very accurate DNA vulvo-vaginal cultures for infection can be obtained. These cultures are very accurate and look at many different types of infections that cannot be diagnosed with the eye or microscope. If the above have been ruled out any evaluated certainly labioplasty should be considered to help improve your lifestyle. Best of luck!