Hi. I think my sensei is a bit sad that we don't have a large female population either. At most.... we have four females on the mat and three of them are always gone for various reasons (college, not training consistently, busy, lazy, etc) Whenever a prospective female comes around, sensei gets all excited. I am the lowest ranking (5th kyu) of the four females. The other three are 1st kyu or above. However, since they aren't there, there really isn't a presence of higher ranking females. Sometimes I wish there were more females in the dojo, but it doesn't really bother me. My sensei has never put pressure on me to test just to be a higher ranking female though. I honestly don't know if having higher ranking females in your dojo would make a difference or not. It could though. Maybe a new person would think "Well if she can get to shodan, maybe I can too." In the end though, I would think that they will either stay or go on their own whether there is a higher ranking female around or not.
If you really aren't comfortable in testing, I would have a heart to heart conversation with your sensei and let him know how you feel. I know I want to feel like I deserve the rank I am. On the other hand, is it possible you are ready and you are just tough on yourself?
If that is the case, he is just getting rid of the time requirement aspect of the rank. Your other options are to train until you feel more comfortable or just not show up on testing day (which I don't really advocate, but I have jokingly threatened to do when I tested last).
As for the rougher throws... are they actually rougher throws or are they just not being babied and are ctually being taken down to the mat instead of to just the point they are being taken off balance? Perhaps more ukemi practice should be addressed to make them feel more comfortable. Like Marc said, although I am thrown more vigorously then I was when I started a year ago, I find the throws to become more soft (when working with someone more experienced). Their techniques are easy to follow, more efficient and because of that, my ukemi is more able to neutralize the throw. Most of the time, my landings are rather soft. When working with a beginner, such as myself this isn't always the case though.
Another issue may be that they are being thrown beyond what they can handle, so nage should slow down to a point that they can keep up and take care of themselves.
Sorry you are in that position. Best of luck and keep us informed.