It's not too bad! Everyone has to start somewhere. I do 2 - 4+ paragraphs depending on interest level with 2 as the bare minimum I ever do. Try describing the scene in addition to character actions, thoughts and things like that help too.
The thing I started doing way back when that helped me increase my post lengths was I started following a simple rule. Never end a paragraph with dialogue. Even if all I'm doing is describe how my character said something, the tone they used and or their thoughts behind it, I never end a paragraph with dialogue.
I started it mainly because I thought it looked tacky to have colored text at the end or the beginning of a paragraph, but it only bothers me when I'm the one doing it. It also increases post length considerably.
I don't worry about post length. Extremely long flowery posts can actually put me off. Details in posts, for me, all have to have a meaning. They have to add to the story, atmosphere, character, etc. Not frivolous just to fill up space or meet some sort of word count.
Vocabulary is also paramount. Like Dread pointed out, long, overly profuse posts that are beefy for the sake of looking good aren't always the best option. There used to be a member here on the site a while back who wrote 5+ paragraphs for PvP posts, and all his work really equated to was "I turned on my lightsaber".
My best advice would be to find your character's voice. Sit down and just type out some random, non-specific scenarios where you think your character would be at the most/least dramatic. Once you've figured out who your character is, you have ~80% of every post done before you even start writing. The rest will just fall into place naturally.