There are really no standard bass sizes. Do a search here and you'll find numerous threads on the topic. What is called a "3/4" is, if anything, the "standard." That roughly translates to around a 41"-42" string length. Individual instruments with that string length vary substantially in shoulder shape, upper bout width, lower bout width, rib depth, etc. The larger ones are sometimes referred to as "7/8" which others would call a "big 3/4." Get the picture? You are definitely tall enough so that you need not look for particularly small instruments. I would say that you should play a bunch of them and see what you're comfortable with but I think that's bad advice for a newbie. That's because what seems comfortable to a newbie can often later turn out to be an impediment to playing. For example, take neck profile. Often a thinner neck feels more comfortable to a novice than does a thicker neck. Then the novice actually learns to play and discovers that it's the thicker neck profile that causes less left-hand fatigue. That's just one example. So, now I come around to the TalkBass mantra:
Get a teacher! Even if just for a few lessons, a teacher will show you proper technique and help you to avoid bad habits and injury. It's a whole different world and instrument than the BG. Take the teacher along with you when you begin your bass shopping-- even if you have to pay for his/her time.
Welcome to the dark side!
Oh, and please fill out your profile. It helps us to get to know you and helps us to help you. Where do you live?