Will lip fillers make my mouth appear wider aswell as my lips fuller? (Photo)

You should start out with maybe 1cc of filler and go from there. You do not want to overdo too much filler in the lips. It also depends on the look you are going for too. You can always add more filler to the lips if needed. Just remember if you are going to do your lips and you do not want to bruise you should not take any aspirins or anything that will thin the blood since brusing can occur.

Hello,

Thank you for your question.

Based on your goals, you may want to consider a
dermal filler to the upper lip. Dermal fillers will not widen your mouth. 

I recommend you book a consultation with a
qualified injector, to ensure you're a good candidate for this procedure.

Take care.

Thank you for your question and for sharing your photograph. I can see your area of concern.  Lip fillers will only add volume and plumpness to your lips and will not cause any significant widening, certainly not of the "gap" .  Unfortunately there really is not an operation to do this.  See an ASPS board certified plastic surgeon for an evaluation and discussion of your treatment options.