I think she might be really scared and confused if she self-identifies as straight and yet is attracted to you. That is probably why she is sending you mixed signals, such as easy laughing at your jokes yet no eye contact. Just let the passage of time help her overcome her fears and come to terms with being attracted to you in "that way".

I also agree with Trippin's advice to seek 3rd parties' company often. Is that doable for you?