2nd birthday celebration - to party or not to party?

[TeaTeaTea]

My DS turns 2 in 3 weeks and not sure whether to have a little party or not. For his first we had the family over, very nice. I could do the same again but thought a little party with 3 of his closest friends would be good. I have an 8 week old DD who I EBF so if she needs feeding I can't very well run around after little boys.

My DS won't really understand that it's a party for him and is just hitting the age of jealousy with toys he's playing with so inviting a couple of other toddlers in to touch his toys is surely going to cause upset right?
Then again my mum suggested just a small, 1-2hr party to include lunch before the afternoon nap and with the other youngsters parents there it should be fine.
Am I fretting over nothing? If so any ideas for indoor activities for 2 year olds incase the weather is bad.