Congratulations on your little one!
The early days are so tough. You know what, I'm surprised the ABA counsellor said that. It's totally NORMAL for little babies to feed a lot in the evenings - it's all part of the so-called 'arsenic' hour. 2-3 hours of solid feeding in the late afternoon/early evening is very common, especially when they're very young.
The best way to tell whether you have enough milk is by the number of wet & dirty nappies - how many are you getting. Right now it's still early days, your milk may not be completely in (it can take a bit of time, and it's not always all at once). The constant feeding is a great way to make sure your milk does come in just like it should.
The gassiness is normal too - it takes a while for their systems to get used to drinking milk (remember, he's only been on the oustide for a few days so everything is totally new to him). And it's quite common for them to be particularly unsettled just as the milk is coming in.

The good news is that it won't always be like this. As your baby gets bigger, he'll get faster at feeding. My DS fed for 1-1.5 hours at a time at this age, by 4 months he rarely spent more than 5 minutes at the breast (and that was for 2 sides). Also, with the arsenic hour (or hours, it's usually 3-4 hours I think) you might find that he's happy to be held and cuddled, as well as fed. Do you have a sling or some other sort of baby carrier? THey're very handy. Another thing to bear in mind is that this sort of cluster feeding can also lead to a nice, longer sleep at teh start of the night - it's a great payoff for you once it happens.

I hope you're able to get plenty of rest and getting lots of help at home