We just spent our whole spring/summer pursuing a diagnosis for my son for his sensory difficulties. He just completed an intensive round of occupational therapy. It was a difficult road to travel, especially because sensory processing dysfunction is not recognized in the dsmv as it's own individual diagnosis. As my son's mom, I KNOW he has these challenges. And I deal with people on a daily basis who don't get it or don't believe in it or just don't take it seriously because his issues aren't visible on the outside (unless you happen to be around for a meltdown).
All of that to say, YOU know your DD. You are her mama, and you spend the most time with her. Whether your DH believes in mental health diagnoses or not, doesn't change the fact that there are clinically demonstrated treatments that make life better for these kiddos when they do get the help they need. For some that is medication. For some, it's not. My son hasn't ever been medicated for his SPD. I was/am on medication for my own ppd/PTSD (am actually nearing the phasing out stage), and up until the day I started taking the medication, I didn't believe in ppd either. :-). Giving the medication a chance to work was a last chance effort to prevent my symptoms from overwhelming me and causing me to commit suicide - which is seriously scary. PPD, ADHD, SPD, are all real chemical imbalances in the brain that are treatable. Some people are able to treat without medication, and some people need medication for a while before they can cope without it.
I remember the desperate feelings of "what the h is going on with my kid!?!?" when we were trying to identify my DS's issues. His OT was awesome at helping him develop the tools to recognize when he was getting overstimulated and overreacting and getting riled up. And we've been able to build a vocabulary around calming himself down. I'm sure there are services like that available to help you set goals for your DD and make life more bearable. ;-)