At times I feel I have trouble speaking clearly & many times people can't understand me but I can't tell. Could speech therapy help?

Can't hurt. How do you know that many times people can't understand you if you can't tell? If you have any questions about your ability to speak clearly & enunciate, i think it's perfectly reasonable to get a professional evaluation by someone trained to assess speech & communication. Just be prepared to pay out of pocket in case your insurance won't.