I read your other recent thread and I didn’t comment as I’m not sure that I have enough experience to help. However, I don’t want to not answer her as you are clearly very down and feeling desperate.
I think you given some good advice on the other thread and it’s important that you seek support from health visitor, GP and nursery. I don’t think that you are a bad parent in any way shape or form. It’s clear that your child is very demanding and anybody will struggle to cope in the circumstances. First of all therefore, you need to give yourself a bit of a slack. Is there anybody you can ask for help to give you a break? You need a chance to recharge your batteries.
As others have said, I don’t think you should be so quick to dismiss potential SEN so push your GP for a referral and make a note or video challenging behaviours so that you can explain clearly what is happening.
However, this will take time so you need strategies in the interim to try and help you cope (as a minimum) but also find some joy in parenting. It might be worth looking at the therapeutic parenting Facebook page. This will have lots of advice on dealing with challenging behaviours in a positive way.
Make a list of people who you can ask for help so that you get a bit of respite. Ask for help. If people know you are struggling, they will want to help you wherever they can. Let the housework slide and just focus on essentials while you’re feeling like this.
Talk. To us, to friends, to your DH etc. Also, talk to your GP about how you are feeling, not just about your DC. It may be that a/he will suggest strategies (which may or may not include medication) for YOU. You matter and you need to look after your own health and well-being too.