Welcome! You've come to a great place to get support and information. Try reading the "stickies" at the top of the page....there's enough info there to keep you busy for a while! I don't think anyone here will be able to tell you if your husband is an alcoholic......that's something he will have to figure out. BUT, if his drinking is a problem for you, and it's causing stress within your family, then it's definately a problem.
I also have 4 kiddos, ranging in age from 16 to 4, so I know exactly where you are coming from. My AH's drinking used to be sporadic like yours, but it increased to a case a day sometime last year. I've been reading everything I can get my hands on, learning all about my role in the family dynamics, and am giving therapy a whirl. With 4 VERY busy kids I've not been able to get to alanon, but I hear it is also a huge help in situations like ours.
I hope you stick around. It's a great place with many amazing people.