UC is probably the hardest map for soloing imo. Pretty much everything after the 120 mark is out for blood and yeah it sucks how easy you can lose a combo or even die from some bs like a zombie grab/whopper tackle combo. Still, you did better than I have. I got to around 125 combo solo and lost it from two zombie grabs one after another (something randomly broke the first zombie off me and the second didn't give me a chance to dodge or counter) that put me in dying state. I haven't really tried again after that.
Same thing happened with me yesterday. Playing as regular Sherry on UC had the combo count at 138 and had killed 138/150 when I died to a whopper tackle :-( my problem is that when I get into it I tend to forget to look at my health. Capcom should do something like Gears were the screen would turn darker/bloodier as you get closer to dying. I know the healthbar is on screen but its easily overlooked IMO.
"Wake up and smell the ashes." G-Man - Half-Life 2