not looking at the actual specs... but just eyeballing the pic... we all have the option of using a number of difference frame sizes in any bike design/model.

you can make this size work for you.
but a couple of comments as to how you have it currently setup
1. Your saddle angle will cause you to slide forward on it, it will certainly cause a lot of your torso weight to be transferred to your arms and the bars, putting undo pressure on your everything from your back/beck to you wrists, hands...
Flatten the saddle to reduce that issue. Saddle fore/aft adjustment will also help balance your weight pressure between seat and bars - that's a bit more complicated - so with that std setback seatpost, just center the saddle on the rails adjustment, and work from there. Sliding the saddle slightly forward, move weight more forward but also makes it just a bit easier to 'spin' a gear - rearward does the opposite. Balance between the two opposites is usually preferred...
2. You'll likely need to lower your saddle to make a flatter saddle work well. DO that.
A good start point for saddle height placement is to put your heels on the pedals and pedal backward while moving - when you're not rocking your hips to maintain pedal contact - that's a good start point. Then ride for some days, making very, very small adjustments to that. The small adjustments will accommodate your foot/shoe size and your pedaling style...
3. Bend your elbows to a comfortable degree, so that weight, shocks can be properly handled rather than straight arms which just send shocks right thru your arms to shoulders and neck.

Ride the Bike for a while before fooling greatly with things.
If you're not riding your bike often over a week period, you'll likely find your will have 'butt ache'... - normal - it's a period of 'adaptation' for the butt... very often not a saddle problem, just time on the bike.
This is all under the assumption that your will ride for more than 20-30 minutes for a ride...
Ride On
Yuri