Gonna (going + to)
Girls, I'm gonna miss you!
Gotta (got + to)
I've gotta go now!
Wanna (want + to)
I wanna buy this car
Lemme (let + me)
Lemme help you!
Dunno (don't know)
I dunno what to say!
Hafta (have to)
I hafta do it!
Wanna is used in written English to represent the words 'want to' when they are pronounced informally. I wanna be married to you. Do you wanna be married to me? Gonna is used in written English to represent the words 'going to' when they are pronounced informally.