i was quite concerned about exactly what you said before it all started too - and my teeth were a bit similar to yours (although not as nice!). i did phone up several orthos, but got the same message, that they only took patients on dentist referrals. so, i was really nervous about seeing my dentist, had this crazy idea that he might absolutely refuse and i'd be stuck!!
when i eventually got to the dentist, he was lovely - and was more than happy to refer me. he had two orthos from which to choose, and set up the appointment for me - at which the ortho was lovely, and was prepared for me to be much less decisive about my treatment! i remember her saying, "so, if you want to go away and think about it, that's fine..... oh. ok. you're absolutely sure, now? well, then, let's take moulds!"
what i found particularly interesting was that the reasons i had for wanting braces (i hated my turned tooth and slightly uneven bottom row) were really different to what my dentist and ortho saw - and they were VERY interested in my bite and angle, and now i can see how much of a difference there was to make. since i was braced, i've noticed the angles of my teeth have changed, my jaw looks better, especially in profile, and my top row of teeth now overlap my bottom (as they're supposed to, apparently... i never knew!) rather than clashing at the tips.
"i'm considering braces to straighten my teeth, can you recommend an ortho? i know my sister was recommended one but you might have a couple others that i can try to see which one i feel comfortable with" - sounds really good, i hope your dentist appointment goes perfectly, and that you're recommended a really good ortho - good luck!