Can I safely ejaculate inside my girlfriend? (she's on the pill)

Yes

Yes. You can safely ejaculate inside her as long as she remembers to take her pill every day at relatively the same time. Wait until she has finished her first pack of pills, however. Its good to let her body take some time to get used to the pill before you begin relying on it. When she starts her next pack, you should be good to go! You will be over 99.9% protected against pregnancy as long as she remembers to take her pills!
Also, remember that vomiting/diarrhea can make the pill less effective as the body may not have sufficient time to absorb the hormones if this occurs. Also, there are certain medicines that contradict the pill and may make it ineffective. Complete lists of these medications are online, but the most common one is antibiotics. If your girlfriend has to go on antibiotics, then you should use a back up method (like a condom) for at least a week after she has stopped taking them.
If you're careful, you'll be safe!

ive been on the pill for about 3 years im fully protected and i say its safe ive done it plenty of times. just dont do it very often. the more you do it the more chances you have of getting her prego. every few days or weeks pull out and you should be good to go.

what if after 3 weeks after taking the pill your partner ejaculates in u is it possible u can get pregnant

There are always the very slightest of chances you can get pregnant. Most birth control methods have a very small failure rate. So small that you do not have to worry about it as long as you use it as prescribed.

So no, if you followed the instructions, you are not pregnant.