OCD and Bipolar disorder can co-exist. One does not trigger the other. The bipolar disorder is a depressive spectrum condition. Thins to look into would be whether or not you've been diagnosed with unipolar depression, if anyone in your family is suffering from depressive disorders
- depression/bipolar disorder. These have a genetic component to them.
Unless you become manic or hypomanic, bipolar spectrum disorders would be ruled out.
The fear of becoming bipolar can indeed relate to your OCD as evident by obsessive worrying/unfound fears.
If your OCD/anxiety is moderate to severe, in addition to self help medication and professional help would be beneficial. You may not be able to manage the anxiety all on your own especially if recently you've noticed a change in your thought process/behavior.
When you speak of mood swings, it would be helpful to note how often are these occurring and to what extent. Are these just regular shifts of mood from anhedonia to morbid depression then to mania, etc.
If the mood swings are not severe enough to constitute a bipolar disorder, it may be a case of cyclothymia
with rapid cycling. Yet, to know for sure, a face to face evaluation with a professional would be warranted.