Hi,
It really is not easy with the tones!
If you have a iPhone or an Android Phone you can check for the trainchinese Pinyin Trainer - that will help you to distinguish the tones better. The application is free to use for a certain amount of times per day. You can give it a try and let us know if it is helpul for you!
Wish you can continue working on your Chinese, a difficult but very interesting language! If possible also try to learn to write it - that will help in the long term!