I’ve been in a relationship with this guy over 10 months now. While I wasn't really sure about it at the beginning (coming from another relationship and – although very attractive – he was not exactly my type, physically), it soon started to feel just like I'd met THE man of my life.

I’ve always been 100% sure I’d never want kids.

My bf and I talked about it multiple times, very chilled. I said I don't think I want kids and asked if it's a deal breaker (we're both in our early 30s now) and he said maybe, but he thinks I'll "come around" ... I said that if he wants kids 100% he should rethink our relationship and maybe look for someone who can be sure about wanting a family, because I just can't guarantee that, but he always replies that it's OK and we'll see what happens in the future.

Now, fast forward a few months – the more I look at him, the more I get these random, uncontrollable thoughts of maybe one day I want to start a family with him.

When I see other kids I don’t necessarily like them or find them cute, and the thought of being pregnant and giving up my life even if just for a few months (I'm very active, sporty and restless) freaks me out big time. BIG. TIME. But then I’m with him, I have this warm loving feeling inside and there’s this random weird little voice in the back of my head saying stuff like “I could really have kids with this man”

Can you possibly start feeling like you might want to have kids / somehow build a family when you never thought you would, just by being really so in love with someone? Or am I weird? 

Of course, people change their minds all the time about things. Having children is a big step, but if you've found someone who you believe would make a brilliant father then that can make you change your mind.
It is a big step to get pregnant, everything changes but that doesn't mean things will change in a bad way. Lots of parents don't like other people's children, you can still be very active and do lots of exercise whilst pregnant,.

I'd say give it a bit longer before actually having children, just to make sure its not just a loved up phase, but if you do decide to have one or two or ten! don't worry about those changes, as you'll easily find different ways of doing your favourite things.

Good Luck!