Hard time at showing my feelings

So I'm an 18-year-old girl in my first relationship ever. I've known him, my boyfriend, for three years already. We're classmates and have a lot of things in common such as our interests and plans for the future. He's ridiculously intelligent and has a truly calm and kind personality. I really never saw him as a possible partner but one day he started showing me clear sings that he liked me: he held my hand, hugged me tightly, kissed my head, and so on. I felt truly loved and so we started dating. We've been together for more than a month now and I really love him: I think his personality is just so compatible with mine. I'm sensitive, emotional, with strong emotions that often take over me and make me feel insecure. And he, as I already mentioned, is just so calm and lovable and his soft voice simply saying "calm down" acts like a sedative on me, plus he loves me so much for who I am. The thing is, I really never expected to have a boyfriend and I have no idea how it works. So when we started going out, I told him to be patient with me. And he's been very patient indeed, but he's also overwhelmingly passionate. Our first kiss ended up in a make out, but I truly enjoyed it. He is constantly inviting me to events at the theater and such, he wants to be continually by my side and I love him.

But then I think that I'm now doing a good job on making him feel loved and secure. Today, for example, we went to see a baseball match and afterwards I went home with him. Now, let me tell you that I'm a very prudent person and never kissed someone before. I genuinely thought that I wouldn't have a boyfriend anytime soon (and that I didn't need one, either) but then this suddenly happened and I'm happy. You can imagine, then, that I'm not the most outgoing girl and relationships are a mistery to me. So, when we arrived home, we cuddled for a long time as usual and then started to kiss. He kissed me so intensely, and our make out was just more passionate than ever, our bodies tightly cramped together. Anyways, when we were done, he just asked me "what did you think of now?". And well, you see, I have an awfully hard time talking about my feelings. I want him to know that I love him, and to be happy, but it is just so hard for me and I don't know why. So I couldn't reply. And when I arrived home, I had a text from him simply saying "I'm sorry". This made me feel horribly guilty. I think I made him feel as if he'd done something wrong to me. I told him not to apologize, and explained that this is all new to me and that I'm not good at talking about my feelings but that I wanted him to know that I love him. Then he said, "I know, that's why I want you to tell me more. At least tell me if it was good / wrong". I guess he's feeling guilty because I wasn't able to tell him how much I loved that moment with him. I'm a very serious person so I can't always show emotions, but I don't want him to ever think that I don't like him. What should I do? He's very quiet too and barely ever speaks but when we're cuddling he constantly asks "what's on your mind?" and I just don't know what to answer. Sometimes when we kiss he also whispers "if you want anything, don't be afraid to ask" and it makes me confused because I don't know what's he referring to exactly. I just want him to feel loved and to be happy and for our relationship to last, because I just know that he's perfect for me, but I'm too afraid I won't be able to show him how I feel.

It is my belief that actions speak louder than words, so I try my best to make him feel loved, but the problem comes when he needs to hear words of affirmation. I'm always telling him how much I love him, but that doesn't seem to be enough. I want to be a good girlfriend, but I'm kinda stuck. I'm also afraid of getting more intimate with him- and I don't mean sex precisely. I find it difficult to take initiative even in the simplest things like holding hands even if I really, really want to. It's scary but I want to do it for him. I just don't know how to.