Yes that’s correct that Co Antrim wasn’t as badly affected by the famine as the rest of Ireland. The people who suffered most in the famine were rural agricultural labourers. However in Ulster many of them were involved in the linen weaving industry as a side line, (made at home on portable hand looms usually in the winter months when there wasn’t much labouring work) and this gave them a bit of extra income that prevented mass starvation. Whilst the overall population of Ireland dropped by about 20% between 1841 and 1851 due to famine and emigration, in Co Antrim the reduction was only about 2%. According to Bill MacAfee’s website. http://billmacafee.com
You wonder why your ancestors left Ireland. I am sure they left for the same reasons that millions did. To find work, or better paid work. Ireland has very few natural resources (no oil, coal, iron ore etc) and so did not benefit from the industrial revolution in the 1800s, the way Scotland, England, the US, Canada & Australia did, which created hundreds of thousands of comparatively well-paid new jobs in new industries (coal mining, steel making, railways, ship building etc). So that was a big pull factor. There had also been a huge population explosion in Ireland going up from about 3 million people in 1750 to 8 million in 1830. There simply weren’t jobs for all those people. In much of Ireland the only employment was subsistence farming topped up in Ulster and one or two other areas with a bit of linen weaving. And then the straw that broke the camel’s back, along came the famine, numerous times throughout the 1800s. The worst period was when the potato crop failed almost completely 3 years in a row in the late 1840s, and then partially several more years after that.
Other factors encouraged emigration, eg early mechanisation on farms. With new machines to turn the soil and plant seed, farmers no longer needed an army of agricultural labourers to help on the farm. So those jobs were rapidly disappearing. Likewise mechanisation had led to linen factories being set up in places like Belfast. These made home weaving uneconomic and so also upset the labourer’s family economy. Agriculture was the biggest single employer in Ireland, but it was mostly a barter economy. Few people had any ready cash save what they could make from weaving or any government sponsored work such as building new roads. So when the opportunity arose to get jobs with a regular wage packet, as opposed to a few pence from your father each week, the decision to migrate wasn’t really all that hard to make. So it was as much about economic betterment as anything
In addition, the British Government often placed adverts in the press encouraging people to migrate to take advantage of land that was available overseas.
There was a massive tide of migration all through that century, including long before the famine. Years after the worst of the famine it’s impact was still being felt across Ireland, and there were still plenty of much better job opportunities in Australia and the USA.
So to summarise, people had been pouring out of Ireland long before the worst of the famine. All the famine did was speed the tide up.