Yes, your insecurity and neediness may be a result of growing up without a dad. However, it could also be caused by other factors such as your young age, your inexperience in relationships, your low self-esteem, and your boyfriend's behaviors that trigger your anxiousness. At this point, though, it's better to acknowledge the problem and work to solve it rather than focus on its origin. Looking to the past will only keep you frozen in victim mode while focusing on the future will propel you to be pro-active.
First, you need to change your thinking. Albert Einstein said: “No problem can be solved from the same level of consciousness that created it.” Therefore, you must accept that how you're framing this relationship is distressing you and, therefore, should be altered.
You're only 25 and this romance may or may not end. By calling this guy “the love of your life,” though, you're putting far too much pressure on yourself and your boyfriend for it to succeed. Instead of enjoying the relationship in the moment, you're worried about the devastation that you'll feel if it ends.
Your insecurity could eventually wear your boyfriend down, leading him to bail. He might get frustrated that you're unhappy and insecure in the relationship and finally accept that he can't do anything about that. Only you can.
It's said that we're not our thoughts but the awareness of our thoughts. Therefore, catch yourself when you're horriblizing a situation in your mind and letting your insecurities get the best of you. Build up your self-confidence by setting goals, establishing strong friendships, creating a deep spiritual life, cultivating hobbies, and volunteering in your community. Reach the point where you know, beyond a shadow of a doubt, that you'll be fine whether or not this relationship survives. I wish you well.