I was so nervous that when bitcoin price dropped to 6000$ I was scared to loose more and withdrew my coins only to regret later that it became 8000$.
Please help me with your advice /opinion.
The decision is really up to you. You may do researcy and make technical and fundamental analysis to help you decide. But the end of the day, Bitcoin price is still unpredictable. There are a lot of factors and reasons that may affect the price of a Bitcoin.
Maybe may tip is determining what kind of investor you are. A lont term or short term. So in that way, you can decide on holding on to Bitcoins for years believing it can be profitable in the long run or sell it everytime you think its going down (active trading)