I think that this is a hard question to really answer. Realistically, in the 150s and 140s before the sack of Carthage by the Romans I think you would have been fairly worried about your future. The Roman threat, though, may have been in the back of your mind. The Carthaginians fought an unsuccessful war against Masinissa in the late 150s, and according to Appian he was a threat after the war (who [Massinissa] was still near them with a large army) (App. Pun 74 [I believe]).

I think in some ways the Roman threat was always present after the end of the Second Punic War. It is unfair to always think of Hannibal as the 'specter of Italy' but never consider the impact of that war on the Punic psyche. There is a good chance that you would have felt anxious about Rome, and in the epitome of Livy we hear of hoarding of wood for a fleet (Book 47), for instance, which may indicate that Carthage was indeed preparing for a return to hostilities with Rome.

I don't know that Carthaginians in the middle of the second century would have been afraid of a Roman conquest, but probably of the faltering of their city-state in general.

NB: This is opinion, as there is really no way to argue forcefully either way from the evidence.