My Punto turns over but wont start,

I have to put it into gear and rock the car backwards and forwards then 8/10 it will start.
Just lately the rocking backwards and forwards then turning over rarely works.
I put the car into second gear with handbreak off push backwards and forward until i hear a clicking, then i turn over and sometimes it starts.

I have changed battery and spark plugs, when i turn engine I can hear fuel pump start. Could it be the starter motor?
Thanks in advance

1999 Fiat Punto 60s
1.2 engine
92000 mileage