You must not think negative of Allah, on the contrary,  should trust in Allah and that He will always give you what is best for you. Always make Duaa and always be content of the outcome.

Please help correct my understanding. If I want something, I make dua to that particular thing. While making dua, I have that thought abt, I may not get it cos Allah will give if it good for me in His knowledge. This means I am not 100% sure that I will get what I pray for. Is this consider that having negetive thought (while praying) abt Allah by thinking that Allah is not giving what I want?