Would P4 be a good option?

Hello Sir, I can't decide the other optional paper apart from P7 that I should be studying for. I appeared for and passed F9 in the December'15 session and I mainly used your lectures and notes for that. The way F9 went, I was fairly confident of not only passing it but achieving a good mark as well. However I just scraped through and was only able to score 51% which means that I was JUST able to get through it. Before that result I was making up my mind on P4 especially because I knew that I could use your lectures and notes again for that as well which I was comfortable with when I was preparing for F9 but the fact that I just scored 51%, what I've heard about P4 that it's probably the toughest paper in the ACCA qualification and the fact that I am working full time, I am having to rethink and choose the other optional paper very wisely and I need to do that quick if I am to appear in this June session. Another fact that might help you in giving a more informed advice is that I am not sure whether I will be making a career in financial management but since I enjoyed doing F9 that's why I was getting inclined towards choosing P4. So in light of the above, kindly suggest what should I be doing. Thanking you in advance!