Timing in music means different things to different people.
To me it sometimes means knowing when to play, and when not to play. Coming in at exactly the right time after a break, or when to make a solo relax or climax. When to play a repeated riff or one long note and when to go “out”. When to play simply and when to play clever fast stuff on the changes. When to use the exact same “time” concept as the rest of the band and when to use your own or play in front of the beat, on it or lay behind it. When to play altissimo, when to walk the bar.
Or when to take a break, when to ask for more money, when to wear a tuxedo or a hawaiian shirt. When to say the punchline.
And most importantly: when to say “sorry”, or “I love you”. (Musically speaking).
Improving your timing, sense of time and rhythm
I was really bad at this when I started out.
There are various things to try, one is to really go back to basics and play long notes counting through semibreves, minims, crotchets and quavers, (whole notes, half notes, quarter notes and eighth notes) then do the same thing while going up and down scales. With and without a metronome.
Especially important is to slow the metronome beat right down, you will probably find this much harder. It takes real concentration but will help you develop an intuitive “feel” for exactly where the next beat comes.
Use legato tonguing on every note. This is important because as you get to playing quavers or semiquavers (1/8 or 1/16 notes) the tongue helps you keep a steady metre.
Very boring but it’s very good practise anyway, e.g. for tone.
Do you find counting syncopation harder? One thing that used to stump me was when a phrase ended on a syncopation, e.g. on beat 4 and followed by a few beats rest. If this happens, the important thing is to NOT try to count the 1st beat.
So imagine a phrase of two crotchets and four quavers (1/8 notes), you play and count:
Dum dum doo be doo dat (…) 2 3 etc…
Tapping your foot to help keep time
When practising don’t be scared of tapping your foot or rocking from foot to foot, however this may not look so good when performing live. It can certainly be off-putting if you are in an orchestra and everybody is doing it. In that situation try something less obvious, such as tapping your tow inside your shoe .
Finally: learn to dance! Any kind of activity that requires body/time coordination will help you develop a sense of time or rhythm.
Above all, don’t think you are inferior or different. A good sense of time is not something some people can do and others can’t, it’s something everyone can learn and develop.