I do not label my feminism! But ...
Yes, working within a system to change that system can and does work. Compared to revolutionary plotting, it stands a better chance of getting further faster. Moreover, feminism is not an encompassing ideology (ie, doesn't have policies on economics, industrial & energy policies, judicial structure, etc, etc, etc) so is inadequately equipped to overthrow existing regimes.
It is thanks to feminists working within existing structures that you have: a vote; equal rights to education & pay; the right to get a mortgage, a divorce, a pension of your own, to stand for parliament; equal pay & opportunity rights; the right not to be raped, beaten or sexually harassed. Thanks to their campaigning and the legal changes they achieved, the society we live in accepts women's rights to live as they choose - certainly more than previous generations; it recognises the merits of gender equality in the home; it censures FGM, forced marriages, institutional rape, bride burning and kidnapping; it supports women as priests, journalists, judges, surgeons and presidents.
Without these achievements, feminist women would not be free to campaign against porn or to question the use of antidepressants, to push for better policing and greater respect or to debate the validity of SAHM life. We would not even be free to speak as we choose, go where we please and wear what we want. We would be voiceless.
All the above is only made possible by democracy. I'm currently worried that we're heading towards totalitarianism by stealth, but that's another discussion. I can't emphasise strongly enough that we must use it or lose it!
I'm not a radfem (except according to quiz Aye posted!) but am what used to be called a militant feminist. I no longer march, walk out and sit in, but campaign continually and promote equality in my daily life. I'm deeply concerned that today's women are losing sight of feminist reality, and fail to observe the fragility of our freshly-won rights.
This has taken a long time to write, so I'll have to catch up later. Thanks for asking, Beach :)