Do most women who choose not to marry or have children end up regretting it later?

Only you know what is best for you. Personally, I don't want to be a lonely, elderly lady. I have been married about 17 years now and after a rough first 10 years I am happy and look forward to my 60s and 70s with my husband. But, if you have great friends and family, and have an active, fulfilling life, I see no reason why you can't be just as happy without "settling down". Besides that why is it called settling down, just because you get married doesn't mean you have to settle down, you just have to fall in love with the right guy!