No you don't 'need' medication - some people may prefer it or find it helpful, some don't.
Personally, I find it annoying how many doctors here (psychiatrists especially) just push meds, when talk therapy eg CBT or others could be equally or more effective..
For some people, meds can be helpful, others may even have bad side effects.. Also, people have different 'levels' of OCD. And this can change with stress levels and such too.. (I've had times when I needed to check if I locked doors, and times when I did't need to..)
Some people on OCD forums have had success with omega3 or such.. You can try this yourself - is it better after you eat tuna or such? (For me, it is..

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There are therapists online who offer OCD treatment via phone or e-mail.. Some very helpful articles and approaches are online too.. Just google 'CBT forum' or such..
Some people even learnt a lot from books or articles and cured themselves, at least they say they did and what they wrote was helpful to me too... I highly recommend learning as much as you can so that you'll know if your therapist is doing it 'right'.. Also ask if they specialize in OCD and what forms of therapy they offer..
Some people even say what their therapists say and have them do is so basic they could probably do it without a therapist too.. If you can get a good therapist that's great, if not or if there are waiting lists, learn as much as you can..