I second, third and fourth everyone who says to see an orthodontist. Don't do these things online.
I had braces as a child, but back then they claimed that you only needed to wear your retainers for a year. Of course, we all know now that this is NOT true.
Flash forward to putting three children through braces and I wanted straight teeth myself because they'd shifted after all of these years.
I went to our family orthodontist and paid for Invisalign. I was offered for braces for half of the time, but let's face it - I'm in my 40's and was NOT interested in that. A side note to this story is that my fourth child did NOT have braces in high school. When she joined the military she decided that the wanted straighter teeth. She did an online "Invisalign" retainer trays type thing and at the end of the day, she wasted her money because although they look better than they did initially, they're not perfect.
If you're a candidate, Invisalign gives you perfect teeth -- and your orthodontist will tell you whether or not Invisalign is for you. It's also $6k in my area.
Hope this helps!