First relationships, 19 F, 18M, Do you think opposites attract?

So Im actually a really insecure person, that's why for my 19 years I never got relationships before, recently I got a new work place and met a guy 10 months younger than I. I liked that he is absolute opposite to me: loud, funny, extrovert, and he liked me back, so start to push too fast, after only 2 weeks of friendship offered relationships. I rejected him and then after 3 more months he offered again, and I decided to try.

Firstly everything was pretty fine, I was happy and felt like my life become more active, but a few things in him made me uncertain. Before me, he got quite a lot relationships, as well he talks almost to everyone at work, and got female friends with whom he drives to mall or just talks a lot, and they in my thoughts are better for him than me, they are as well loud, active...

So we together just second month now, and our relationships already start to get worse, I told him my thoughts and he said that he really loves me and I should worry less.. but I honestly cannot, sometimes I really think that I should break up, but the main issue is that we already decided to trim together at holidays in December and bought tickets... Do you think I should talk more to him, or even do something? I already dont feel open and free with him, this make me insecure..

Wanted to add that he is quite childish, got jokes which could sound offensive, and actually do make me sad, we spoke about it, and still sometimes I hear it. (I understand that we just 19 and 18, and its still a teen age, but maybe I wanted something more certain, just dont really want to end my first relationships that quick, maybe after some time I will understand that everything actually wasnt that bad?)