The tips I could give would be, hmm...
Try looking into online counseling. There are a few ones who do Skype little sessions. Maybe it's cheap?
Get a "personal coach". If you could find a friend of yours who is understanding and wishes to help you, that person could help you a lot, even if they're not a professional.
Sing to Japanese female singers. But whoa. They have generally high voices, right? The challenge is just there: try to emulate their inflections, but whilst staying at a comfortable range for you. A good point to focus on for me was to analyze the point where their voices "break"/"switch" and how it sounds when it does (there's a special-ish vibration). That "break" alone can make heck of a difference. Once I've succeeded in imitating it, my singing voice became much better IMO.
Try to imitate people you hear speak. But it's a silly thing to do when there are people around, right? I personally did it a lot when watching anime. I've practiced "sonna koto nai shi", "shina nai de, Kurosaki-kun" and many more phrases many times around. Trying them over and over again, trying to sound credible as the character you are trying to imitate helps to grasp some "keys" to a better voice, I think.
Try to feminize a song you know that is sung by a guy. It's hard, but it also helps putting the finger on female elements.
Sing a lot in the shower. I don't know if it's the steam, but it helps me give my voice more range more easily.
Try to identify the point where your voice goes falsetto and do prolonged notes on that point precisely, trying to push it up slowly.
And also, don't overdo it! Whenever I push a whole lot in frustration for not being able to reach that one note, my voice's capabilities go down for a few days.
I hope I helped.