Some bloody drainage from the nose is normal especially if the procedure includes a septoplasty and turbinectomy. This drainage should decrease slightly every day. Rarely there is significant bleeding a day or two after surgery or extremely uncommonly on the 7th or 8th day after the rhinoplasty....
Splint should be getting loose by itself and come off easily without pain....if it's really stuck no reason it couldn't stay a bit longer. sutures might pinch a tiny bit, especially if scabby. certainly not something to be overly concerned about. the "cleaner" they are, the easier they will come...
Rhinoplasty takes weeks to months to completely heal. You most likely will have swelling over this period, but it should become less and less noticeable. 18 days is extremely early in your healing process. Just follow the advice of your surgeon and give it some time.