You can give both JEE and NEET if you are unsure about any one of them. But if you want to go for only one(jee/neet) then analyze your biology and maths properly because physics and chemistry are common subjects in both the examination(jee and neet). Give mock test for jee as well for neet since it is the most effective way of preparing for an examination. If you are scoring well in the jee mock tests then you should definitely go for JEE else you can opt for NEET.