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Definitely don't feel ashamed for venting! You're right that this is a safe space where nobody is going to judge you. You can post as much as you want about almost anything. I'm not sure the name of the mindset you're in, I'm sorry about that.
It's great that you're starting to be more in tune with your emotions and are learning that there is more than just sadness there. I think that becoming more aware of your emotions is one way to learn more about yourself and come up with solutions and coping mechanisms that are specific to the specific emotion.
It's also so great that things are looking better for you right now. Having your own room, making progress towards your own phone, and less arguing are all great things! I'm happy that you're at least in a bit of a better place right now.
There is comfort in the sadness and comfort in the things we are used to. It may be part of what is drawing you back to some of the old habits and the thoughts of attempting.
Remember that even though your mind tells you one thing, every situation is different. There may have been no permanent damage the last times, but eventually it does start to add up and take a toll on your body. I don't know what your method of attempt was and due to our site rules you can't share, but the permanent damage can become serious. For example, certain methods can lead to needing to be on dialysis or having permanent liver problems, and I know you don't want that. And we definitely don't want you to die here. We want to see you thriving and living your best life.
But I would try to remove the methods you have to any extent possible. For example, put them into a safe so they are harder to access, or put them somewhere where you'd have to make an effort to get to them. That way, by the time you get to the methods you'd have calmed down a little bit and have had the opportunity to think more rationally. Maybe event try to get out of the house entirely when you are having urges, or go sit with your parents. I do that when I have urges to self harm. I go watch TV with my parents as a distraction and because it would get a little suspicious if I up and left.
If you do get a strong enough urge to act on your feelings I strongly encourage you to tell your parents and head to the emergency room. I know you may not want to but you definitely would need a break and a bit of respite to start to develop a new mindset. Some time away may help.
Try and find things to replace the behaviors. For example, when you start to feel an urge to harm yourself, take a cold shower so it can reset your body. It kind of is a shock to the system and acts as a reboot. Maybe draw or paint on yourself instead of doing something harmful so you can look at something beautiful. At least it washes off when you're done. Also reward yourself for not acting on your impulses. Maybe watch your favorite comfort show/movie after, or do an activity or hobby you like.
I know it's hard, but you can get through this!