RONS dont worry about inverting in turbulence the chances of that happening are extremly remote (in my 33 year experience) unless you make some bizzare control inputs. The important thing in severe turbulence and severe is defined as likley to damage the aircraft is to try and not to make control inputs that will increase the loading on the aircraft.
I have had three very nasty experiences in CB where the aircraft was put into large pitch and roll attitudes that alarmed me to the point of near panic.As in two we were also struck by lightning I cannot begin to tell you how frightened i was was for a brief instance, however there was never any fear of the aircraft inverting--my main fear was that the AHs would topple so some limited panel unsusal attitude recoveries may help your confidence as your most likely encounter with severe turbulence is likely to be in CB.
Its also nice to bear in mind that your C150 ihas greater G stress limits than all modern airliners, so stay cool.
PS my excursions into CB were as a result of unservicable weather radar, embedded cb with an aircfaft with no weather radar and all on passenger carrying flights not instructional