engagement advice?

We have talked about getting engaged and we both want to but because of personal issues with his family we are having to wait to make it "official". We have had a lot of problems with his mother, and her family, trying to split us up. We've had times when we've had to get police involved because my family and I were receiving threats from them. So for these reasons we are having to wait to make it "official" which I hate because I want to celebrate the happy occasion. 

We've discussed when we plan on finally being able to announce without the risk of problems. And when we plan on getting married. And to be able to afford the wedding we both would like on our income it would take several years to save. We also have money already set aside for a ring and we've been saving for our wedding for a few months already. 

I've had a lot of negative comments from the very few people who know, and it's been all sorts of comments. We've had comments such as we are too young and we don't know what we are doing, or we are being silly if we think by the time we will be able to afford getting married we will still be together. I've even had negative comments on what engagement ring we have picked out because I prefer something small I've gone for a plain basic white gold band and a cubic zirconia in a princess cut. Because of this people have commented that it's cheap and tacky but the ring is who I am it's my style, something simple and elegant. 

But I have questions fo you married and engaged ladies out there..

1) what was your engagement ring like?

2) does it really matter what stone your engagement ring has?

3) does it really matter on the cost?

4) how long were you engaged before you got married?

Any positive stories as well are welcome ladies. Let's share those happy memories/occasions. 

Please no negative comments ladies, I do know we are young, things can change, but we are very sure this is what we both want and how we both feel about each other. We might be young but he means the world to me, he's been my rock through a lot of things in life and he accepts me for who I am, I love him more every day, I honestly can not wait for our future together.💕

Thank you ladies!!