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We use numerical simulations to model Gaia DR3 data with the aim ofconstraining the Milky Way bar and spiral structure parameters. We show thatboth the morphology and the velocity field in Milky Way-like galactic discmodels are strong functions of time, changing dramatically over a few tens ofMyr. This suggests that by finding a good match to the observed radial velocityfield, v_R(x,y), we can constrain the bar-spiral orientation. Incorporatinguncertainties into our models is necessary to match the data; most importantly,a heliocentric distance uncertainty above 10-15% distorts the bar's shape andv_R quadrupole pattern morphology, and decreases its apparent angle withrespect to the Sun-Galactocentric line. An excellent match to the Gaia DR3v_R(x,y) field is found for a simulation with a bar length R_b\approx3.6 kpc.We argue that the data are consistent with a MW bar as short as ~3 kpc, formoderate strength inner disc spiral structure (A_2/A_0\approx0.25) or,alternatively, with a bar length up to ~5.2 kpc, provided that spiral arms arequite weak (A_2/A_0\approx0.1), and is most likely in the process ofdisconnecting from a spiral arm. We demonstrate that the bar angle and distanceuncertainty can similarly affect the match between our models and the data - asmaller bar angle (20 deg instead of 30 deg) requires smaller distanceuncertainty (20% instead of 30%) to explain the observations. Fouriercomponents of the face-on density distribution of our models suggest that theMW does not have strong m=1 and/or m=3 spirals near the solar radius.

Gaia DR3 data consistent with a short bar connected to a spiral arm