Have you IDed your type of bamboo yet? I am living in Taiwan and there are many species of bamboo that are no good for bow making. Typically you want something grown at elevation where the weather is colder and the boo should be between 3-5 years old but NOT OLDER. Older bamboo looses tensil strength. What you have already done in the picture looks fine, but You won't be able to get much of a bow out of it due to the lack of thickness. The best idea would be to do what you have already done, then get 40 grit sand paper and a flat block of wood. Use this as a simple means to even the surface and rid it of any unevenness or dips. Don't think this is a quick task. Take your time. Once it is totally flat, do the same to another piece. Now you have two pieces you can laminate together with some strong epoxy. Before laminating, you can also roast the belly of the bamboo for a while with a heat gun or CAREFULLY with a torch or open flame. This should take well over 30 minutes per lamination and you should never burn the grain black while doing this. Just lightly brown it and allow the heat to travel completely through for an extended period of time. After heat treating, go about gluing them together. There are plenty of build alongs on this site to teach you how to do this. Immediately after binding and glueing, you can glue in recurves or make a deflex-reflex style bow using a form or blocks...again, you can find this in build alongs. After the glue has thoroughly dried, you can go about tillering like any other bow using your angle grinder at first, but I always switch over to sandpaper and razor blades as soon as the stave starts bending even a little. It is easy to take off too much boo in a laminated bow. The heat treating, if done correctly will make the bow a better shoot and help it avoid setting too much which is a major problem with bamboo...particularly in climates like the Philippines. I'm sure you guys have lots of usable tropical hardwood there as well! I can pass you on a list of wood we use here in Taiwan that you most likely have in your area as well if you want. Good luck.