How can I get referred for female sterilisation at 21?

I have known for several years that I do not want children and after a long time of suffering painful periods due to contraception methods not suiting me and now being told that I am no longer allowed to stay on the combined pill which has been the most effective for me (4+ years) due to weight gain and smoking risks. 

I have researched the complications, methods, and side effects of this procedure in depth so know understand that this is rarely reversible and a permanent form of contraception. 

The only issue I have with going to my GP with the request to be sterilised is that I am 21. Even though I am this age, I know motherhood is not for me and I do not want the risk of becoming pregnant any longer. 

Is there any way I can make the GP more likely to refer me for the procedure instead of telling me to wait several years until I'm older 'incase' I change my mind. Which I 100% know I will not have. 

Thank-you

Don't do it, I regret it because it will cause a host of other symptoms with in the female body. More cramps, pain ect. Doctors are oblivious to this. Not worth it.

Stay away from the pill and iuds they will cause iron and copper dysregulation. In the long run just puts havoc in the body and doctors don't even know it.

Please think twice before going through with it. I wish I knew then what I know now.

What would you recommend for me then? 

As I know I 100% do not want children and I feel it's a waste of resources to be on contraception costing the NHS for tablets etc.

(just trying to gather as much information and opinions as I can) 

Thank-you

You don't want to deal with messed up hormones in the end. Use protection or abstain when you are ovalating. All other methods come with a price on your health.

All the best to you in whatever decision you choose.

Thank-you for your response, I'm going to discuss my options with my GP and see what they suggest for me