Human beings are born with a set of aptitudes, and you cannot change them any more than you can change your hair and eye color. This is well documented. You cannot develop true perfect pitch if you were not born with it. You cannot become a great baseball player or artist if you do not have the proper aptitudes, or we would have millions of star baseball players or artists, etc. You can improve what you have, but there is a natural limit.
The problem is that it is hard to know what your innate aptitudes are. It is really necessary to try many many different things, and variations within each thing. If you think bass doesn't fit, try drums. If your rhythm sense is not good try something else other than music. Don't limit yourself.
Remember - you can only be interested in something you have experienced - there are countless things out there for you to try and some will fit better than others.
There is also an easy way to find out all about your aptitudes - what you should and should not be doing. There is a non-profit research foundation that has been testing people around the world for nearly 100 years. Check it out -
www.jocrf.org. EVERYONE should do this - the world would be a better place. If kids knew their aptitudes they would only take the courses that are right for them, they would do better, feel better about themselves, learn more and get better grades easily. Likewise - we could all be working at jobs we loved and were good at.
Sorry to sound like an ad - but I'm a believer. It changed my life and those of everyone that has followed my advice about this.