How much power should 14.4W LED strip consume?
Let me try a simple analysis with no specs


my initial reading was you had two 39 in series = 78Ω, so I will show Rev B
let 14.4W / 60LEDs = 0.24W /LED including 1/3rd of Pd in 78Ω
let's assume they "cheated" ( or exaggerated marketing with no specs) 
V+=14.4V ( car alternator = 14.2V nom)
e.g. 14.4V*1A = 14.4W

thus 60 LEDs in 20 strings = 50mA per string 


and Vdrop on both R is 50mA*78Ω = 3.9V 
with Vf = (14.4-3.9)/3led=3.5V (cheaper quality LEDs)



Conclusion

12V will never achieve rated power for these StripLeds, you need a battery and charger or a 15V or 14.4V power supply, because they are rated for Cars but still work on 12V since the LEDs add up ~9V at low current.

These will also be running near maximum temp so suitable for semi-trailer trucks with forced wind cooling. lol.

Rev B

Analysis with updates on Rs current limit using two 39Ω in parallel=20.5Ω


Given 60 5050 LEDs/m in parallel(P), series(S) array 20P(3S + 20.5Ω)
your results of 2.0A at 12V for 2.95 meter = 8W/m and not 14.4W/m
Now what would we expect at 14.2V with 2.9V/LED?


or a rise of 2.2V or almost 20% in power source to match opt. alternator voltage in cars
do we expect a linear incremental rise in power due to series R? no but,
a 20% rise in voltage, results in a 40% rise in power if it was linear
we need almost 6.4/8W=80% rise to achieve 14.4W, so it is quasi-linear
this is because the most of the voltage rise is across Rs=20.5Ω 
You measured 2.9V/Led @ 8W/m thus If= 8W/(20S * 12V)= 33.3mA /string
thus V across 20.5Ω * 33.3mA= 0.68V
my trick is knowing LED ESR is due to incremental V/I above 2.7-2.8V
i.e. (2.9V-2.7V)/33mA=6.7Ω assuming your reading was accurate

now I can estimate power vs voltage for arrays in two ways, Can you?


such as 20S(3P+Rs) using LED ESD &amp; threshold Vth or from specs



http://lianhaolighting.en.made-in-china.com/product/kbCEjFuMQZVg/China-LED-Strip-Light-LH-5050-60P-12V-.html