Ive been a lone parent for the majority of dcs lives. My eldest is currently doing her gcses and it's only in the last few weeks, that I can see I've been a good enough parent to my 3.
I'm watching her as though it was the first time I met her and I see a wonderful person, who I'd want to be my best friend if I was 16 too.
Shes had a tough time for various reasons, and I think these exams have tested not only her academic ability but her work ethic, her resilience, her moral compass and just about every aspect of her personality. It has also tested my ability as a parent to be there for her as needed, when to be kind/soft, when to be more encouraging, and when to be downright firm.
With my current viewpoint I can see that my other younger dc will be ok too.
But at your stage and for a long time, I really was waiting for someone to tap me on the shoulder to say 'sorry, we've just realised how shit a parent you are and therefore you can't keep them anymore'.
I remember a friend of mine visiting her dying FIL, she had just found out she was pregnant but had never felt maternal. She was thinking about her options but couldn't envisage having an abortion. They told FIL the news and discussed her reservations, and he responded saying 'just love the child, everything else will follow". It touched me then and still does to this day.
A pp touched on this saying they love the bones of their child. That's all you can do. Everyone is winging it.
I've also had a parenting mantra that if my child challenges me about something when they are adults, I want to be able to look them in the eye and say "I did the best I could at the time". Because life changes. Circumstances change. Be it health, finances, working pattern etc. But whatever has been going on, I've dug deep and done the best i could at the time. I've made mistakes, who hasn't? But once I've realised it was a mistake I've done my utmost to minimise the negative impact of it.
There have also been many times when I just didn't know what to do. Talk to people you trust. Garner others opinions. Not only does talking help you to realise your inner instincts, it often leads to help being provided.
But above all, give yourself a break, we all have days where it seems like we've failed at parenting...and we're really all just winging it.