21st in 2 weeks - who to invite?!?

[D]

I'm turning 21 in 2 weeks time. Unfortunately, I was a socially awkward and quiet guy back in high school which reflects in the size of my social circle and at times, makes me feel lonely.

I only have 2 friends from high school who I hang out with regularly. This year, I met a group of people in university and I feel comfortable talking to one of them, who invited me to his birthday a month ago which I attended.

However, I don't hang out with the group much in general, despite their repeated invites to join them. Another person in the group invited me and everyone to their birthday next month.

I'm really dying to have a party since I have not done anything over the years with friends - I didn't even have an 18th. I don't want to go through my 21st alone.

Am I expected to invite everyone else in the group if I want to invite that guy who I feel comfortable with? In general, they are just acquaintances.

I am also contemplating inviting a few old friends from primary school who I have been out of contact with for almost 10 years. They have never been invited to my previous birthdays though - would it be weird? I also have another group of acquaintances I met at uni before transferring courses - they'd always invite me to their picnics during the holidays. Would it be appropriate to invite them to my birthday?

My main worry is when they see the small guest list on Facebook - it would show I am a loser.

Also, what is the right paying etiquette given the makeup of the potential attendees? I'm just thinking of dinner in the city, followed by a few games of bowling and a few drinks or hitting the clubs (if someone brings it up).
At the same time, I am worried it'd be awkward since I usually keep to myself when I hang out with the 2 acquaintance groups but since it's my b'day, I'll be in the centre of attention.

[no mercy]

when my son was 18 i booked him bowling and gave him money for the bowling for everybody and maybe some refreshments during the game. they went out afterwords, where they paid for themselves (i hope, i didn't give my son money to pay for everybody in bars or wherever they went). and u do not need to put a list on facebook, u could just CALL people and invite personally, and i do not think it is wise to invite a big group of people for bowling and drinks - it will be too expencive for u, because dear, u MUST pay at least for something if u re inviting them for your birthday. it is called birthday PARTY, this is not a party if they need to pay for themselves

[Blondebear]

Go to a bar with your closest friends

[bluebellbkk]

I don't have a strong view about anything you've asked about, but one thing is ESSENTIAL, and that is, what ever you decide about payment, you MUST make it clear to your guests in advance. Nobody should go to a party under the impression it's all paid for, and you're a guest, when in fact you're expected to pay maybe not only for yourself, but for other people who ordered lobster salad and Champagne while you had just a pasta dish and some beer.

Decide what you want to do - pay for everyone's first drink, then they're on their own; everybody buys their own drinks right from the start; you'll cover the food if they buy the drink: whatever. But make it crystal clear when you invite people.