I had sex with my boyfriend, we use a condom, but before that his penis went in briefly without any protection. Before that I haven't had sex in 3 months. Also I dropped the pill 3 months ago, got my period 3 months after I dropped the pill, which was a week before the intercourse. The next day after sex I had an ovary pain, and I've had it ever since, for about 3 days now. It's not very bad, but I 'feel' the ovaries from time to time. What could that mean?

IT means you will have to wait several weeks, see if you have your next period and if you don't take a pregnancy test.

Condoms have a normal failure rate so they are not 100 percent effective by any level. So even with it, there is a chance. Now it is just the waiting game.

My periods are very irregular now, had one 10 days ago which lasted a day and a half, and before that was 3 months ago. This could be a very long waiting time. Is it possible to feel pregnancy symptoms the next day though?

No you will not "feel" anything the next day. The spotting for a day or two is a sign of pregnancy at times.

But you wait about 5 weeks after the sex and take the test.