Are these sentences in Chinese right??

Are these sentences in Chinese right??

I'm sorry to post this under "Notebook" instead of "Answers", but I can't find my way round virtual Chinese keyboards... so I'll have to keep posting pictures of "my Chinese handwritting".

In these sentences, I intended to write:
• My dogs are big 我的狗很大。
•I study Chinese at home 我在家学习中文。
•I work at home  我在家工作。
•I have studied Chinese for a month 我学习中文已经一个月了。
•I have studied Chinese for a couple of days 我学习中文已经有好多天了。
•I am 23 years old 我23岁。

Thank you veeeery much for your help!:)