Just finished making my muffins. I haven't done any baking for so long that my tins were covered in cobwebs. As I was making them I realised why I don't do it very often: unless things go exactly my way I get into a temper and mess it up. I was swearing at my muffin cases because they wouldn't stand up straight when I put in the mixture. I still didn't manage to get the right texture, so no idea what I'm doing wrong. I had so much left over I had to throw the rest in a brownie pan. I dumped a whole bag of chocolate chunks in but god knows where the bloody things went. I don't think there was anything wrong with the recipe but the execution left something to be desired, as you can see.
This is a good start, do not get discouraged. That was the most basic of muffin recipes and by the looks of them, you did well. They have the standard, 'cracked' tops' and they do not look burned.
The recipe was for both muffins and loaves so no harm there.
It sounds like you need to develop more patience, relax, and enjoy the experiments.
You DO NOT just dump add ins into your batter; you gently fold them in. If the chunks were too large- then a smaller variety or chips would work better.
Since the texture is too soft (we call it fine crumb) and you prefer a denser crumb in your muffins and I can offer you a recipe that replaces some of the flour with oatmeal if you like that flavor.
I have used ground oatmeal in chocolate chip cookies with good results but have not tried it with muffins. It does change the texture and adds flavor. Let me know if you would like to try again.
Good try and edible; could have been worse.
Don't give up- this is a good start, although you seem to have a
unique approach, I think we can make a baker out of you, yet.