Hey. First of all, that sounds really stressful, and I’m sending you virtual hugs if you want them.
Second, this sounds like it’s likely due to your depression. Loss of romantic and sexual attraction/interest, as well as flattened affect (not feeling emotions very strongly anymore—happiness, sadness, etc.—basically, feeling numb) are well known symptoms of depression. You’re not broken or abnormal or anything; this is a normal (and sucky, but normal) symptom of depression. Mental illness, just like physical chronic illness, goes through periods where it’s worse and periods where it’s better. That’s probably why you felt better for a bit and then felt worse again.
I’m really sorry your parents aren’t okay with you getting therapy (and presumably also meds, which are very often necessary in conjunction with therapy). That makes it a lot harder to get help. Depending on where you live, though, there are still ways you might be able to access care. Because you are 16, you are old enough (in the US—I don’t know about other countries) to have patient confidentiality, where your doctor can’t legally tell your parents what you’ve said to them or what they’re doing to treat you unless you are in imminent danger of hurting yourself or others. This means that you might be able to access care yourself, without your parents’ permission, as long as you are able to pay the copays (this is tricky if you want to keep it a complete secret from your parents, unless you have the means to bypass insurance, but can theoretically be done). It’s likely easier in places with universal healthcare, because there aren’t copays and insurance that your parents could track, but I’m not 100% familiar with how that would work in places other than the US, so don’t quote me on that. Your school counselor would likely also have resources for you, and the internet is full of information about how to access mental healthcare as a minor.
I don’t know your specific family situation, but perhaps the simplest (though maybe emotionally hardest) solution would be to sit your parents down and have a real heart to heart conversation about the ins and outs of the state of your mental health/lack thereof. Really talk about the nitty gritties and lay bare the scariest and most difficult things you’re dealing with. That might get them to accept that you need help they and your bootstraps are not able to give. It could also be a terrible and dangerous thing to do though if your parents are abusive; I don’t know them, so I can’t make that call. You would need to decide if that’s a good idea or not for yourself.
I wish I could give you more help. You’re not broken, though; you’re just depressed and in need of proper mental healthcare. Once your depression is well-treated, you should feel a lot more like yourself again.