If I am not wrong this blog/site is made by one of esteemed members here, well she writes her own spells so it must be true...
Apart from these you should find some tumblr blogs that are made by witches as they write their own spells :)
And if you still want, this guy
Can help you in writing some specific spell
I will advice you to 'ask' and talk with witches with experience and request them to share their spells...
Another option is : Go to any member whom you find 'knowledgeable' and goto their history and try to find if any of their spells can help you, if it does dont forget to send them a thank you note.