Embarred teen gay male needs some advice...?

Well, I've had a boyfriend now for 4 months and we've done nothing ual apart from kissing and touching etc. We both agreed we'd like to take things further as we both feel comfortable with one another. The issue is... I consider myself to have a tight and if I'm honest I think we'll have issues getting his in my . I tried using 'baby oil' to lubricant my and inserting my fingers to see what it feels like. But, my muscle just wants to be tight all the time so I have discomfort trying to get my fingers up. I'm really scared because I love this guy and want it so bad. What should I do? :(