Is my gap too big for bonding? (Photo)

Yes, the space is too wide for a couple reasons:1.  The composite bonding will be unsupported and will break off easily. 2.  Even if the bonding is done it will make your front teeth too big and wide and look bad. I I would advise you to seek orthodontic help again and this time follow that up with regular retainer use.  This is going to give you the best end result that you should be able to more easily maintain for years to come. 

Your picture seems a bit distorted, but based on what I can see, the central incisors (middle teeth) are already too wide for the other teeth.  So, no, boding would not yield an esthetic result, Minor orthodontics, followed by bonding or veneers on the lateral incisors (second teeth) would likely give your the smile you desire. Best of luck.