Oye, do I ever know this situation! Some SN kiddos can hold it together out in the world for awhile and it makes getting help a nightmare. My SN DS is that way. They (meaning the doctors/OTs/psychs/etc.) couldn't reconcile my descriptions of DS with the cute little kid sitting in my lap.
Kinda like taking your car to the mechanic, and when you get there it won't squeak.
I was totally and brutally beaten with the "paranoid mommy" crap. Two doctors (DS's docs, not mine) even wrote scripts for anti-depressants for ME! Most of the people we saw in the early years were totally unwilling to hear what DP and I were saying. I got free books, referrals to discipline seminars, or just sent away with some platitudes. Meanwhile, our lives utterly and completely sucked.
One tune I started playing loud and often was the one I called "My other kids are not like this." I'd slip it in here and there, like "This is so hard; my three older kids were so different!" Or "We used to get compliments on our well behaved children all the time, but Carter is just so different." Just trying to drum into their heads that I knew how to raise children, knew what a problem looked like, and my through-the-roof stress level was a RESULT, not a cause, of Carter's problems.
We just kept trying and trying and trying. It took several years (I know, not what you want to hear), but finally landed in the office of a fabulous developmental pediatrician who actually knows how to listen and who trusts what DP and I say about what happens in our house. He knows that Carter's problems are real and devastating, not just minor annoyances in an otherwise happy childhood. Honestly, we've been working with this dr. for over a year now and I still sometimes hesitate to call him because I forget that he's going to listen and take me seriously after all our terrible experiences!
If you're on state aid, have you asked for a case worker? When we were on public assistance, we were assigned one and she helped us through the process for awhile. Try the insurance angle at any rate. They might be able to point you in some new directions. Also, check online and in the newspaper for parent support groups. No one on earth can help you more with the mess that getting help can sometimes be than parents who have btdt.
Make a pest of yourself with confidence. You didn't cause this. It's not about poor parenting. Your DS, you, and your whole family deserve help. I just say this because my confidence got so beat down, and maybe you're not there. I finally got so desperate at one point that I told DP that I would never again leave an appt. w/o some kind of action, be it a referral, a new appt., a script, something. I swore I'd stay for 3 days if I had to. Never had to, but it was so bad, I think I would have done it!
Anyway, enough from me and it's time for bed. I hope you get some help really soon!