>> i haven't used social medias much since this summer, but i miss posting about my day and interacting with others. <<

You might like to explore Recurring Posts. Not only can you use those in your blog, if you like consuming them, you can search for other blogs with that kind of content. A lot of communities have a weekly or monthly gather post, and a few have a daily one like Just One Thing on awesomeers. Watch people's profiles and addme or friendzy entries, because some will list their posting frequency, which is helpful if you want high interactivity.

>>i used to spend all day making css themes,<<

See communites like style_system dreamscapes, dreamcodes, and dreamwidthlayouts.

>> making friends, <<

I made a list of Addme communities for Follow Friday:
https://ysabetwordsmith.dreamwidth.org/13330527.html

>> and commenting on other users profiles. <<

I don't think DW profiles have a comment function, but many bloggers have put up a sticky post introduction with the same kind of information.

You might also like the custom Community Thursdays, where people make a point of commenting or posting in communities and listing what they have done there in their own blog.

>>i always loved the blingee gifs.<<

See graphics and nondenomicon. If you particularly like animated icons with gif, see also communities like iconthat and icons.

More generally, you might find it helpful to browse recent materials for newcomers like my Twitter Exodus post or twitter_refugees.