Wishing to be engaged indefinitely?

My boyfriend and I have been dating for 2 1/2 years and living together for 2 years this month. He's 26 and I'm 23. We are very happy and very serious and talk about marriage and kids all the time. But lately, it's been frustrating when introducing him or talking about him to people who don't know us well and referring to him only as my "boyfriend". That word alone doesn't appropriately quantify our relationship or the seriousness of it all. We're both grad students right now, so we don't have the funds or time to get married - but have talked about doing so in the not too distant future. Before now I haven't pressured because he doesn't have the funds to buy an engagement ring, but I recently found out that I've inherited my grandmother's engagement ring - something so beautiful and special to me - meaning that he doesn't have to buy one if/when he proposes. What I'd really like is just to be engaged indefinitely - and wait to set a date for the wedding until we're both financially ready. I've mentioned the ring to him briefly and my sentiments regarding our status as "boyfriend" and "girlfriend" but really just don't know how to drive this all the way home with him. I need to stir some emotions up in him soon because we are visiting my family in early July and that would be the perfect time for him to ask my mom for it and for them to get it sized for me. Am I being ridiculous? And if not, what's your best advice?