I am a lady only a few years younger than you who has been dancing for a little under a year. I still very much consider myself a beginner in many ways; however, my skills have improved a great deal since I began and I have taken private lessons in speciic dances for about six months. I have found that, although private lessons are much more expensive than group classes, they are worth their weight in gold, and make a huge difference for many people, so this is something you might want to consider.
I understand your frustration when ladies let you know in one way or another that they do not want to dance with you because of your skill level. I had this happen to me early on with several "gentlemen" who made no bones about being frustrated with my lack of knowledge of more advanced steps. Many of those same people are now happy to dance with me, but I still remember the embarrassment I felt in the beginning. This was perhaps amplified for me because of the fact that, as a person who had done other types of dance over her life, and also a great deal of nightclub "freestyle", I considered myself quite the dancer when I began at my dance studio and figured learning ballroom would be a piece of cake. It was quite the humbling experience in the beginning!!
I do have one comment with regard to your being reticent to ask "very attractive" ladies to dance, or not wanting to ask somebody whom you see has a higher skill level than you. Although I know you have experienced what I can only categorize as rudeness on the part of some ladies (I would NEVER leave a man standing on the floor in the middle of a dance because he only danced the basics) - but please don't make assumptions based on these criteria. As my own dance skills have greatly increased, yes, I admit that I sometimes now feel a little bored when I am asked to dance by a gentleman who is obviously a complete newcomer, and frustrated by the "two left feet" thing, especially if it is a dance that I have learned really well and love, such as the smooth dances. Also, although I am no spring chicken, I am generally considered very attractive for the age I am, and I have experienced situations in which men I would have loved to danced with and get to know better have avoided asking me because they saw I could do a particular dance really well and they were afraid they would look silly to me. I would not have looked at it that way, and when I DO get asked to dance by such gentlemen what I generally do now is think of it as a good chance to review my own basics and perhaps even help another dancer along a little bit. Sometimes, too, these men are fun to chat with while dancing. Since they are not very advanced they are not concentrating on all sorts of different patterns and it can feel relaxing. And just because a lady is "very attractive" does not mean she is going to laugh at you or put you down. Yes, I know it has happened to you, but when a person behaves that way, just remember that they may be attractive on the outside, but not on the inside and don't feel bad about yourself.
As far as stepping on a lady's foot, I can tell you that I will always fondly remember the time I stepped on my own foot while trying to learn Viennese Waltz.