Does anyone else feel more comfortable telling certain friends things and not others?

For example, I have a friend who has been in my life since primary school but I don’t feel comfortable sharing anything personal with her. Like my partner and I trying to conceive or where I’m planning on getting married etc...

Then I have friends who I’ve only known for three years or so and I tell them everything.

I don’t know if it’s just because she’s not really supportive of myself/her friends changing (marriage/kids) and having an adult life while she is still single and struggling... which makes me hold back.. or is it usual for people to be closer to some but not others?

I spend a lot of time with a work colleague and I would class us as friends but I wouldn’t tell her my life plans either for some reason. Again she’s single, older than I am and struggles with life...

I don’t have a lot of close friends. I’m pretty shy and closed off so if I am sharing personal things it’s because I trust completely.

Maybe I’m just not wanting to bother them with my personal dramas? Maybe I don’t feel like they’ll support me? Maybe I prefer to share with friends who have had experiences in the areas of kids and marriage?