I for most of my 20s I adamantly didn't want kids then in my late 20s I started having doubts and worried that I'd regret having none.
In my early 30s I got pregnant and it's been way better than I ever imagined. I have this sense of contentment and happiness that I've never experienced before. It's like I still have all exactly the same surface emotions but at my core I feel this real sense of happiness.
I'm not saying everyone should have kids or it would be like that for everyone. There were lots of people on a recent thread who said they were happier before children but I cannot relate to that at all. Honestly all I ever heard about was how hard and awful it is having kids and I wish someone would have told me how amazing it was too as I was terrified.
With me though I think I did always want kids but I thought I'd be bad at it which is what made me not want them. I was always "good with kids" but being around other peoples kids was also really draining. It is tiring with my own but doesn't drain my social battery in the same way. Its the same as how being around my DH isn't as draining as being around other people.
I was also worried about the lack of freedom and not having free time and all the noise. Actually, the things I should have worried about are not the things that I did worry about.
Being around my son is my favourite thing. I am genuinely surprised at how much I enjoy his company and he's only 2. Him making noise doesn't bother me in the same way as it does other children and I have to keep reminding myself to be aware and alert of his noise so I don't accidentally let him be really loud and annoying to others as I don't notice it the same way.
Someone at work the other day told me they can't imagine having kids because they can't imagine having to spend money on their kid instead of themselves and they said they feel they are too selfish to do that. It made me smile because I had the same thoughts before having a child. But when I buy him things it's not like some martyr situation where I have to go without so he can have it even though secretly I wish I could buy something for myself. Getting him a new tractor toy honestly gives me so much joy like I'm a child again. Buying for him is so much more fun than buying for me. If anything it's selfish in the sense that I do it for my own joy.
Really not saying all this to convince you. Just to say that all of the hard bits you hear about are true but for me it's still the best thing I've ever done. That might not be your experience though. I do think the fact I went into it expecting it to be awful actually might have helped as it far exceeded my expectations.
I also think that there's this pressure on yourself because it's the biggest decision ever, and it is, but I don't actually agree that you need to be 100% sure to have them. I've never been 100% sure on any decision in my life. I'm a doubter. I worry. I think you just have to not put too much pressure on yourself to make the decision.
Either path will bring you happiness and challenges. Either one has it's good and bad parts. I was so paralysed with indecision and I read the first page of a book called the Baby Decision and couldn't continue as it made me cry.
Years later I realised I cried because very deep down I wanted a child but I was also telling myself all the reasons it would be better if I didn't. And I was scared I wouldn't be able to cope. I did know my answer deep down the whole time - just not consciously. I didn't need the book in the end but I have heard it's a good book.
Good luck and remember that either decision is a good one and will have a lot of great times ahead.