Congrats on the push-ups...
The last couple of months I've been getting down on my bedroom floor when I'm getting dressed in the morning and doing push ups, I'm doing 15-20 no problem now, but the first few times I was doing only 5 or so... and I consider myself pretty upper body strong... So practice does make it easier... I also noticed that my upper chest is really showing a difference... I do them when I'm waiting for my deodorant or face cream to dry, when I would otherwise be just standing around...