There really is no appropriate age. At this point what your parents say goes. I agree that the parents of you and this boy need to be there for supervision. Do his parents agree with yours?? If they think it is okay, maybe they could talk with your parents to ease any concerns they may have. Let your parents know that everyone is on the same page and have similar goals and values. Talk with your parents , make sure you do not do anything to show them you shouldnt be trusted.
You can do as you wish at the time you leave your parents house and have the responsibility for sheltering, clothing and feeding yourself. Until then you are subject to the decisions of your parents in all matters and it's a wise person who realizes this and accepts their authority with grace. Most parents will allow their children more freedom when they are convinced they are mature enough to handle it but loving parents will always err on side of prudence.
Perhaps they're more uncomfortable with the thought of you growing up and the possibility that it insinuates he's your boyfriend? Maybe if it wasn't just him over but 1 more friend, maybe would be easier for them to accept? It also makes a huge difference if you guys are hanging out in the family room or kitchen versus your bedroom, even if your parents are home. As a parent, I prefer my kids hang out at my house with their friend/friends than somewhere else where I have no clue who they are with or what they're doing! Talk to your parents and ask them what is acceptable...respect their decision- they love you very much, that is why the boundaries ;)
Believe it or not, teens tend to not tell the truth all the time. I remember telling my parents that my GF's parents would be home and we were just going to watch tv. We knew her parents would not be home. I got caught when my mom called hers and found out the truth. We got away with it several times. We never had sex, too afraid of getting pregnant. Bottom line is your parents support you with a place to live, food and clothes and probably anything else you want or need. As long as you live in their house, you follow their rules. No questions asked, you just do it.
I'm sure they are this way because they want to protect you... Many young teen pregnancy and dysfunctional relationships... I think with supervision it shouldn't be a problem with you... And even if they did trust you... Do they trust the guy enough to let you be with him alone...I really don't see a problem with that .. Someday when you're older and have children of your own you will see that the love of a parent goes deep that if it takes them to protect you from anything ever happening without them being there ... They would rather make sure you're older ... More knowledge and wiser.... Love them and appreciate how much they love you.... There are many parents raising children that belong to there own child who they once trust and let them do as they pleased and consequences lead up to a baby who now becomes there responsiblity..... Talk to your parents and see if you can work something out with supervision... This is just my opinion though... Goodluck