I think the first thing is you can't force your relationship with her. It should fall into its place on its own. I think the reason many triads fail is because of the insistence that everyone try to love everyone equally.
Polyamory works mostly by communication. You should be able to bring up your feelings to her. You feelings for her may wax and or wane over time.
She should understand about NRE (new relationship energy). It is a pro and a con of polyamory. Understanding that helps many people deal with jealousy since it lasts about 6 months (and longer for long distance relationships) on average.
Jealousy on your part is fine to feel, but it is a symptom of deeper feelings. Try to figure out what makes you feel jealous. Like it is a fear of losing him? Is it envy at how much time they have together? Once you know that, you can focus on the central issue.
It would help if everyone involved read up or got involved in the poly community. That way they can have access to other who live like you and offer advise on similar issues.