Found: environmental prevention boy from future to stop world collapse

The main character is in school and plays football(american). He is like super strong, and fast. He is told to lay low by his parents but during one game he breaks a school record. He is at a dinner when he thinks he sees a figure watching him. He goes home from his date and his dad takes him immediately on a drive. While his dad is driving they start getting shot at by some ray gun thing. They crash and his dad tells him to run. Before he leave he sees his dad pull out a weird looking gun. He goes and meets this one nice girl and she turns out to be an evil girl from the future (i think she might be an alien). He finds a telepathic dog and escapes. He ends up meeting another girl who is also from the future but is on his side. she tells him that he comes from the future and was sent to prevent their destruction. (if i remember right she has some shape shifter ability) she trains him and ends up falling for him and tries an advancement. he turns her down and suddenly they are attacked. using a special suit he is able to fly away. He then meets some other dude. The girl that helped him is there also(he starts to fall for her too). Apparently there is some device on this guys island that will help the main character. he ends up finding it but the girl he is falling for dies in the end. she revels that the prophecy said they would get married but that wont happen now she is dying. she dies and he goes back to his hometown and goes by his girlfriends house.(everyone in the town seems to have forgotten about him) he thinks that she has probably has forgotten him also. he turns to go but hears a voice. her voice. boom end of book. i want to read the series. any help would be appreciated.

Firestorm by David Klass.

>2 MissSquish: Thank you sooo much i have been trying to find this forever!!