i think now is best time to quit trading.
because if i see the chart if btc prize in several months, the price is stable

That's not the right decision at this moment. If you find bitcoin trading not profitable you could shift towards the trading of altcoins as altcoins are in the rising side and giving high profit.
Trading is a very smart job honestly because there are very very rare chances of occurring loss when you do trading because most of traders have stocks of bitcoin..