My teeth have thin enamel, very yellow but no cracks or rough edges, how long will they last?

I went to the dentist and he wasnt very forthcoming with information about the exact condition of my teeth just did a comprhensive exam and gave me a treatment plan consisting of 17,000 Dollars now im 19 years old i cant afford that. I have cut out all soda's i am brushing twice a day now flossing once and using mouthwash twice a day. My teeth are yellow and on some i can see where the enamel is more towards the gums the bitting edges of my front teeth are a little translucent but not very much. My teeth arent severly sensitive, not really a pain as much as i can actually feel them. I dont want to get crowns nor can i afford them. If i keep up the good oral hygiene and stay away from the acids and sugars can i keep my teeth from getting worse?