Is she just a friend or more?

I am really reaching my breaking point in my relationship. My boyfriend and I have been together for a little over a year. He has a female best friend (who I will refer to as Dee)which I was okay with at first, but something seems a bit off. I have never met her face to face but I know of her. My boyfriend is originally from New York and usually takes frequent trips there to visit his family and his best friend also lives there. Anyway, they are always on the phone, he is always texting her while he is spending time with me and I just feel like I am constantly competing for his attention when it comes to her. He flew to NY a couple days ago and when I called him yesterday, I asked him what is he doing. And he said “Oh I am taking Dee to get her eyebrows done” I was like ummm okay then. He said he will call me back. And never did. And the night before that he had hung out with her all night. He keeps trying to reassure me that nothing is going on. And that I should trust him but he goes all out his way for this girl. Maybe I am overreacting but why she couldn’t take herself to get her eyebrows done? But I don’t know. I am not the type to try to come between my boyfriend or his female friends because obviously they were in the picture before I was, but certain boundaries should be set. I have tried to express my feelings to him about her but he just brushes it off. I have male friends but I have set boundaries since I have been in my relationship. Or maybe I am the problem and need to work on some trust issues. Any advice would be appreciated.