I was reminded of a joke：A foreign friend, pointing to a Chinese character：只，Is this a TV? hahaha。

你好安杰！鉴于你的中文水平，相信我的中文回答你可以领会。首先，汉语学习是一个漫长的过程，和英语一样。有很多独特的用法和语法，他们来自于语言产生国家的生活习惯，历史，故事等等。不像德语，俄语，他们有严谨的语法，给你组织好了框架，学好之后只用向里面填字填词。 前两天我看了一个视频，受益颇深。这里面说，语言的学习，不要用有意识去学习，更多要用无意识去学。什么意思呢？不要有意的去记新语言的语法，单词。就是多和使用这个语言的母语者去交流，去沟通，不要害怕错误，哪怕只有有限几个词汇，反复用，反复记，然后扩展新的词汇。总有一天，你的词汇量会和母语者一样。同时，你已经了解了这门新语言的构成，发音，架构。所以语法问题也迎刃而解了！

Laurence, a British diplomat who is very good at Chinese once told me that when he was being trained at Peking University on the special course for British diplomats, he could do a negotiation on intercontinental ballistic missiles completely in Chinese but often got totally stuck at the hairdresser's when he tried to discuss styles and lengths. So difficulties happen to all of us. You will succeed in the end.

袋熊=dai4 xiong2=wombat 催眠=cui1 mian2=hypnosis 霍乱=huo4 luan4=cholera 鹦鹉=ying1 wu3=parrot 权杖=quan2 zhang4=crosier 窈窕=yao3 tiao3=sylphlike 菩提树=pu2 ti2 shu4=pipal tree To be honest, I did not know 菩提树 in English until you wrote it here. I only know it is a Buddhism word with some religious meaning. For more information, I have to search online. So it is normal to be unfamiliar with some certain subject if it is new to you. For your last question, the answer depends on your objective. If you want to become an expert in a short time, the answer is yes. But if you set a proper goal and learn by steps, the answer is no. You seem to be very strict with learning which is a good spirit but if you find it is really hard to do something, maybe you have not find the right way. Keep learning and you will learn better, because you have already learnt so much.

The tones are the easiest with only four types which can be learnt by enough listening, speaking and reading aloud; The characters can be learnt by reading and writing; the grammar is more complex compared to English, because it is not as precise as English grammar, so you do not have to focus on every details as it can be confusing even for some native speakers. But it still can be acquired with enough practice, especially by listening and reading, but it takes time to know it better. I also find it hard to learn from a book if half of the words were not familiar to me. I believe that happens to any language if the book is both complex in content and words. Considering Chinese words has a history for 5,000 years. It is impossible to remember all the words even for the linguists. So it is normal to meet new words from some books. But in most cases, there is no need to remember them all. There are only 2,500 common Chinese words nowadays and 7,000 are less common according to some researches. So you just need to know most of the common words first and remember those you need. For others words, you can learn later if you still need. It is good to keep curiosity in learning and ask questions. But it is better to control the speed of learning and focus on the main points. Some words will stick in your mind if you spend enough time on them. Those words you forget how to say is not difficult compared to what you have already known, the only reason I can guess is lacking of practicing.