You are above 18 that mean legally you are not a minor. You are an adult; you can decide for your life. You can choose a partner and be in a relationship if you want. As you rightly said you both are in love so I don’t think there is any issue in having a physical relationship with the person you trust in. I guess you and your partner are taking precautions for contraception to avoid unwanted pregnancy and infections. Because if one doesn’t, possibility of an unplanned pregnancy most of the time takes toll on the girl’s life in our society.  
You have mentioned the age difference of almost 11 years between you and your partner. Though it is quite a difference (generally in our kind of society it is not looked upon as a good thing to have) but here also I don’t see any problem as such. What is important in a relationship is to have trust, commitment and love.
I assume that you might be perusing your studies currently and have a plan for the future regarding your professional career as well as personal life. So take the Driver’s seat of the bus of your life and also take the responsibility of the decisions you have made or going to make. All the best and take care…