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.
That is a normal mistake when you are dealing with bitcoin. The dips in the cryptomarket are huge, and it's hard to deal with them. There is a lot of speculation surrounding bitcoin, and most people still don't know if they should call it a bubble or not, so every time they see these dips they think it will be the death of bitcoin. Thing is, that BTC has been proving us wrong over and over again. After these big dips, the coin recovers and eventually sets some new records in price, becoming stronger than it was before.
It's hard to trade bitcoin, I would say that if you just hold your coins you will probably be just fine. Of course that we all want to take some out of the price fluctuation, and right now, I will try to buy at the dip, and them hope for a rebound and sell a small % for profit, and keep doing it, as the price keeps increasing. Note that I'm only doing this, because I believe in BTC. I think it will have global acceptance, so it's price it's still low at the moment. I'm buying at the deep simply, to get more coins for long term hold at a better price.