Wow! What a wonderful trip for you! Things have really changed since I was there in late 90s! I have friends that have been since. I think you have a great advantage being from Switzerland, especially if you frequently tolerate higher altitudes ! Despite training and doing several backpacking trips before my trek, my body just couldn't handle it over 13,000 ft, and I had to turn back at Thorung Phedi at 14,600ft. I got bad altitude sickness with fluid in my lungs and was glad to have companions to help me. The only cure was going down, despite Diamox. I am a pharmacist, so was well versed in the presentation of the altitude sickness. Despite that, Nepal is one of the most beautiful places I have ever been and have no regrets. Congratulations on such a great trek as a solo woman!!