I think that you should see your doctor first because he or she will be able to help you to find a good counselor and will also be able to make sure that there is no medical reason for your moods. You must tell the doctor that you really want to begin counseling because you think that it would help you. Most doctors understand that we do not always know why we feel the way we do and they are usually very willing to help. If you cannot afford to see a doctor or counselor, please write back to me and let me know. I admire the fact that you and your boyfriend are trying to understand what went wrong with your relationship.
Relationships are very hard to keep together because people do change over time.
If you and your boyfriend can spend some time together without arguing, then seeing him may be a good idea. But, if being with him is going to cause you to become upset all the time, then it might be better to spend less time together. I think that it would be good if you could put your energy into trying to understand yourself right now instead of blaming yourself and your moods for everything that is wrong between you and your boyfriend. He must give you some time to look into your moods and feelings with the help of a counselor. If he does not understand your decision, you should not let his opinion keep you from getting the help that you want.