I tried to find you too but couldn't. So I did a bit of googling and found an article from 2009 that says if you change your username, because of a bug in Twitter, you won't show up in searches.
Strange if this is the reason why you aren't showing up as it appears to be a 4 year old bug! If this is why you aren't showing up, then you may want to start a new twitter account with new name so you do show up.
You have to be very pro-active with Twitter to build up a following and a presence. Follow people who you are interested in and many will follow you back. There are great many SEN people on twitter - I follow many dyslexia specialist people. I even follow my LA but I have a feeling that it's not the SEN department but just the touchy-feely what-a-wonderful-county-we-are twitter account!
Whenever you write an article for your blog, tweet a link to it with the relevant hashtags. Tweeting will drive traffic to your blog and vice versa. As well as linking to your blog, tweet good quality tweets regularly.
I don't tweet/blog about SEN matters but I am a regular tweeter/blogger on another subject. Let me know if I can help you.
Oh, just remembered - I use the same twitter name as my blog so people can easily find me using the same name for either media.