Stopped payment Check from Customer. Do I have a case?

I am a freelance artist. I paint custom portraits. My site is www.bellaposhportraits.com A former customer, who is a Veterinarian Doctor, has ordered more than 40 paintings in the past. She has always paid me with a check, paypal or Etsy. On June, she ordered from me another 14 paintings. She sent me order by email. She sent me the 14 photos she want me to reproduce and paint with a few amendments. Stupid me, did not request a deposit as she has always been a loyal customer. Not even a contract but have all proof of her order. She then Approved the paintings with a Wow, Gorgeous etc. Twice she asked me "when I was going to ship"... She sent me a check for payment for $6780 before I delivered. I deposit into my Wells Fargo account and check was cleared after 3 days as specified by Well Fargo personnel. Having my check cleared, of course, I started using money to pay my colleague, materials, expenses, etc. (Remember: She paid me, once she approved and Before I delivered. After t