I'm pretty sure I am lesbian but my parents seem to think it's a phase?

I'm almost 15 and I think I might be lesbian.
In year 5-7 (about grade 4-5, so about 9-11 years old) I was always the girl with a 'boyfriend', even though it consisted of hugging and holding hands, nothing else. :lol: I never felt anything towards them, it was just the thing to do. When I was about 9-11 ish, I had a best friend who I was extremely protective over, I love cuddling her at sleepovers, I got jealous of anyone being close to her and I always wanted to be with her and I found her beautiful. Also, I used to get so upset over being away from her in case she found someone else etc. But I found it normal and just being a best friend but now I realise it was my first girl crush since I still have a huge soft spot for her. I had a same-sex experience when I was about 11, with a girl from my football team as I kissed her and I liked it, a lot more than even holding hands with a boy. When I was about 12, I noticed that I kept looking at girls a lot and i found myself looking at them differently to how I looked at boys. I think I was questioning at that point.

So at 12 years old, I tried to push it aside in many ways but it always stayed there. Eventually, I couldn't hide it from my parents so I told my mum in a flood of tears I thought I was gay, and she told me that it's a phase because she hasn't noticed any signs that I'm gay (a bit stereotypical). I developed a crush on a girl that lasted for quite a few months, but it never happened and even now, I get a fuzzy feeling when I see her. I've had a few female crushes now, as well as being 'obsessed' with female celebs but Half a year ago, I came out because I got involved with a girl (who I'm still involved with) and I'm unbelievably happy with her. I'm out as bisexual since it's easier than immediately Coming out as gay, but I feel like it's a lie as my interest in boys is very little. But now, it's been almost 3 years since I first started to realsie and I've lost basically all my interest towards boys. I still know when I boy is attractive and I still think he is attractive, but I don't want to get with them and I don't have any interest in sexual or emotional relationships. I am sexually attracted to women and I am emotionally attracted to them, but with anyone I don't want sleep with them or be with them until I have an emotional bond with them. There's only one guy that I can think of that I've ever really liked, but now I have no interest in him and I can't stand the thought of being with a guy, although I'm not a 'man hater'.

My parents seem to be slowly realising that it isn't a phase but they still say 'when you bring your boyfriends on holiday with you' etc, although they know I have a girlfriend.
I'm 99% certain that I'm a complete lesbian, but my parents are in denial in many ways.
Do you think I'm gay?
How can I make my parents understand that it isn't a phase?