Get in a car (with my dog) drive to the nearby store. Get resources to sustain myself (as a minor I really can't fight of wildlife or fend for myself very well). Drive until I find a good place to stay and maybe stop off at animal shelters to release dogs/cats to defend myself from wildlife attacks. Find a lab and start making humans in petri dishes, manipulate their genetics so they will survive and repopulate the earth.
Also, I would make sure to not go near any zoos in fear of any of the animals escaping and stay with my dog(s).
tbh id go out and party like crazy, fuck shit up, and do any drugs i come across, before killing myself because it really isn't worth living if im the only one left.
Rob all the supermarkets and start ravenging for food that lasts. Then "borrow" a small loan of an million dollars. Start considering the least painful suicide attempt. Or start considering creating an human/ape cross species, if that's possible, to try keep the genes alive so that way if aliens do exist they could try and create another human from the hybrids. Or try to preserve myself like an pickle.
Also, I would make sure to not go near any zoos in fear of any of the animals escaping and stay with my dog(s).