My nose feels stuffy, but when I blow it, it's hard to blow anything out. Why is that?

Anti-histamine. You may simply have a lot of mucous and inflammation in the sinus areas that is not able to be "blown" out. Consider antihistamines like zyrtec (cetirizine) and even possibly one with a decongestant - zyrtec (cetirizine)-d.
Nasal congestion. Although there are many nasal decongestant sprays ( afrin, dristan etc.) they should never be used for longer than 48-72 hours and always followed by over the counter nasal saline spray or gel. The congestion is caused by swelling of the delicate membranes ( mucosas) lining the nasal passages. You may want to consult your private physician regarding the short term use of nasal cortisone sprays .