两节中文课

我今天早上和晚上上两节中文课。
It's better to write like this: 今天我分别在早上和晚上各上了一节中文课。
Today I had one Chinese lesson respectively in the morning and in the night.

在十点第一节课不容易，因为我还生病了(I am still sick?)。
早上十点那堂课很难熬，因为我生病了。
难熬：having a hard time to deal with

You can also use "堂" instead of "节". 

In this case, I know you want to indicate that you're still sick so you suffered during your morning Chinese class. Now I omitted "还" is because the main reason that you suffered during the class is sick, but not "still sick".

If you really want to say "I am still sick", then you should say"我还在生病"。

Here's an example for you to use "我还在生病" in a conversation:
Let's suppose that I've been sick for a week, and my friend, Ann, she knew that I was sick last week. Now she almost forgets that I am sick, and she invites me to a concert. Then I reply her: "Sorry, I can't go with you. I am still sick, I need more rest.". My reply in Chinese:"对不起，我不能和你一起去。我还在生病，我需要多休息。"

我也觉时间到了我准备新抽认卡，因为我不能记得新词语。
我觉得是时候准备新的生词卡了，因为我无法记住生词。
I reckon it is time for me to prepare new vocabulary cards as I could not manage to memorise the vocabularies. 

I will omit "也" as I reckon it's unnecessary to use it here.

Use the term "生词" (vocabulary) instead of "新词语" (new words).

两节中文课

我今天早上和晚上上了两节中文课。在十点上第一节课不容易，因为我(还)(delete it)生病了(I am still sick? Yes, it means you were stick at that time. If you want to say you are still sick now, you should add another sentence. 现在我还在生病。)我也觉得时间到了准备新抽认卡(what do u mean? 准备新的抽查？，因为我不能记得新词语。

Work so hard???? even if you were sick, still insisted to study!

两节中文课

我今天早上和晚上有两节中文课。十点的第一节课很不容易，因为我还在生病了(I am still sick?)。

两节中文课

我今天早上和晚上上了两节中文课。第一节课是在早上十点的时候，真不容易，因为我的病还没好。我觉得，是时候准备新的抽认卡了，因为我记不住新词语。