Okay so here is the deal and some truths. You will NOT get the 6-pack you want before the end of summer; you might but I seriously doubt it. Here is my reasoning and advice:
1) You are very lean and do not have much muscle on your frame. A 6-pack, means abs muscle. With this you will need to train HARD and Heavy while eating a lot to gain those muscle (there will be some fat that comes along). Like someone listed already, definitely do SQUAT (fully down 90 degree or parrellel while focusing on stabilzing with the core); do ab machine with weights and like all muscle keep reps btw 10-15 with 3-5 sets. Make sure to rest so it develope.
2) Once you pack on the muscle, then you will need to trim down the bodyfat so it will show which may take you a month (from what I see you have a high metabolism so weight lost is easy for you but gaining is going to be hard).
A six pack is a badge of hardwork or god-given DNA. It shows that you have displine, toughness, and dedication. Stick to a clean diet, get the knowledge to know how you can get the 6-pack, and finally pushing yourself to stay on the course. If a 6-pack is easy, everyone would be walking around with one.
Good luck man, some of the reply may seems a bit harsh but they are pretty accurate. I'd guess you are about 12-14% bf as well. At 7%, your vein are just popping out like crazy man. One more note, if you noticed your upper abs are pretty small and under-develop compared to the lower, squats will fix that.