The Market Rasen-based rider recorded fifth and seventh-place finishes in the first two races at Donington Park, but crashed out of the third race at Coppice.
Starting race one on Saturday from a front row grid position, O’Halloran was running second through the first two laps, but began to slip back.
After a mid-race lull, caused by a lack of rear grip, he began to close back up to the leaders in the closing stages, moving up from sixth to fourth.
He was then pipped at the final corner by Tommy Bridewell to record fifth place at the flag.
In race two on Sunday, O’Halloran started from the second row, but an incident involving another rider left him down the field in 10th.
He fought his way back up into seventh place on lap 19 of the planned 26 when the red flag halted the race because of rain and a result was called.
O’Halloran said: “It’s not been the easiest of weekends.
“We’ve been chasing something all weekend, made some changes for Saturday and improved the feeling, but in the first two races I struggled at the start.
“For the third race we made some more changes, but I was quite far back on the grid which made things difficult.
“The bike felt much better, I had a lot more confidence on the brakes and I felt like I could ride the bike how I wanted to again.
“I’m really happy with that and I’ll take that away from this race as obviously a crash isn’t ideal. It’s our third DNF of the year, which isn’t what we want.
“I want to go fast and be at the front, I don’t want to be messing around in seventh or eighth, so we have to keep pushing and looking for the feeling we are after.
“Once we nail that on the head I’m confident we’ll be at the front.”
O’Halloran leaves Donington Park holding 10th place in the rider standings on 42 points, with the next round at Brands Hatch from June 14 to 16.