What should I do and Who should I invite?

Ok, sorry this is kinda long. Ok so, my bday was ages ago bt since I started a new sch I culdn't reali celebrate it cos every1 was new n I didn't know any1. So now it's a few weeks on and I have gotten closer to a few people. Well not just a few people. I'm busy on saturdays so im only free on suns for a small get together. I dunno whetha i shud invite my old friends first or my new on a sun. Whoever I invite i dunno what to do, I'm fifteen so it has to be something good. Anyway when I do invite my new friends I'm not sure who i should invite. I'm close to these four people more than the rest but if i invite them i have to invite these other three people (i like them just not as close, and seven is not too big) then though if i invite them i have to invite these other two people because otherwise i will feel guilty but I like them. And if i invite them i have to invite these other two which i hardly know because they are very quiet but still are in the group of friends. If i invite all of them I duno what I would do with them because my mum doesn't want more than seven max in the house. Then there will be like eleven people that come which I think would drown me. Help!!!