Hia 444pavel, Your plant is beautiful, however i do think your plant is on a stand by mode. Could you take it inside to get temp above 15 at night? Below 15 is a problem when a plant is that small. When bigger it is fine but for now more light, but surely more warmth during the coldest part of the day. If it is in soil use a plastic bottle that you cut cover it. It could take up to 2 weeks to recover from the slow growing mode.
all the best