In English, we don't really say "hit the bottleneck," if what you're trying to say is that your progress feels like it has slowed down, or "leveled-off." In this case, we might say "I have reached a plateau," or simply "I have plateaued." Just in general, not just in learning English, but in anything that requires progress to be made to improve, whether it is learning a language, or becoming a better athlete, we say that someone has plateaued if their progress has slowed down. The imagery here is that you are climbing a mountain, and then you reach a plateau, which is defined as a usually extensive land area having a relatively level surface that is higher than the land around it.

是遇到了瓶颈的意思吧？就是酒瓶子脖子那里卡住了，出不来、下不去的意思。

Hitting the bottleneck is a phrase used to describe particular circumstances in a figurative way. It basically means that the flow of something has been slowed down because it has been overloaded or has met an obstacle. In the UK you hear it in traffic reports, e.g. ‘traffic has bottle-necked on the M25 near junction 14, due to the closure of two lanes’. What is immediately understood here is that the traffic, which was flowing along on 4 lanes, has now been squeezed into 2 lanes and so has slowed down, like the liquid coming out of a narrow bottleneck as opposed to out of a bucket, if that makes sense. In is sometimes used in technical situations at work etc, e.g. to describe a network issue - as in ‘there is too much traffic on the network at this point, it’s causing a bottleneck and data flow is slowing down’. Basically it works as a metaphor to describe any situation where the flow of something -data, traffic etc - is compromised because of the overloading or narrowing of whatever it is it is flowing along.