Owning the Rohan expansion has no impact whatsoever on your chances of winning the lottery. If you were unable to enter the lottery, there are two possible problems.
1. Your characters weren't high enough in level (which seems doubtful if your join date is any indication; the inability to get above level 10 in the span of 2 years seems unlikely).
2. Your characters are bugged. This is the most likely issue. It was a LOT more common with the old lotteries. The servers would fail to receive new information on characters, resulting in it not updating the character level and, in some cases, even displaying deleted characters. Perhaps even characters that had been transferred from one server to another.
If you think you've fallen prey to the 2nd possible problem, I think the appropriate choice of action might be to submit an out-of-game ticket, but I'm not sure.
R5 100 GRD Marevayave - Leader of Riddermarked For Death
R8 100 MNS Fayah/100 LM Siennah/100 HNT Dinenol/100 RK Dhurik
100 CHN Alachas/85 CPT Dinfaerien/60 BUR Dhax/35 WDN Godoric
R9 100 MNS Fayeh (alt Wilya) - Lonely Mountain Band @ Landroval