How do we get rid of thoughts like Jannat is too good to be true?
You need an Iman boost. The best way to do this is
a) read lots of the Quran.
B) read stories of the Sahaba.
Here are some links: http://www.islamibayanaat.com/EnglishLiterature.htm. Hayatus Sahaba is an excellent source for stories of the Sahaba. Mufti Taqi’s English Qran translation is there too. http://shaikhsohail.wordpress.com/2009/04/25/hayatus-sahaba-lives-of-the-sahabah/. It may also help you to be a in a good Islamic environment for a while, so going out in Jamaat might be good for you.