CRF450 your a big dude you need a big bike. A CRF250 will be too small for you very quick. IMO I would try to get a used 125 and then move up.
13 F10 535xi JB/B working on it
11.75 E93 M3 MR/Black Stock (wifey)
11 F10 535i AW/CB Mods Gone