My lips are slightly bigger than usual, but do not hurt at all. Is this related to my allergies?

Possibly. Sounds like angioedema. Angioedema is an atypical swelling of dermal and mucosal membranes. Being allergic can play a role but so can many other things. Treatment is antihistamines unless you have throat or tongue swelling or difficulty breathing or swallowing. Then call 911 or get to an er.
Maybe. Lip swelling is a common sign of allergic reactions, however certainly not exclusively. Typically, if lip swelling is secondary to an allergic reaction it's short-lived, meaning hours, not days. However, if the allergic reaction is to something to that you are constantly applying to your lips, then it could last for days if you continue to reapply the offending agent.