You'd be 7 months pregnant by now if you got pregnant back in April. I highly doubt you're pregnant! But definitely talk to your mom about getting a pap smear (sexually active women NEED to get them once a year) and so you can speak with a doctor about your irregular periods.
I agree with ashiepooh. I don't think you could be pregnant based on your intercourse date. It is important for the future for your body to become regular. I had to go on the pill at 18 because I would go 2-3 months without a period and then severe blood loss for 10 - 12 days to the point I became anemic. I was an athlete in college and that can alter your cycles too. You should at least have some sort of contact with a dr. to make sure your options for having children - in the future - are not compromised. You can bring up the subject by telling your mom that your cycle is irregular and making you feel "not right". I hope you can open up and let her know your sexual habits as well. I know it is tough - but she loves you and wants to help if you need her.
I think that birth control would actually help regulate your periods. I doubt your pregnant, since you had a period between now and the last time you had sex. I'd tell your mom you want to get on birth control because you never know when your period is going to come, and it'll help wonders!
I would probably say your not pregnant! Pregnancy tests can be very reliable now a days. And sometimes when you think you may be pregnant, you start getting, what you will think are 'signs' but it's probably just a coincidence. Your boby playing tricks. By all means get checked out though. x