dont really have the money for a plan b plus...

Talk to your mum no matter how hard it is. Be honest with her. Yes she'll be mad and disappointed but she'll be pleased that you went to her for advice.

If you are honest about it and own up to making a mistake, then she should respect that and help you get what you need.

As another option, talk to another person that you trust and who could get the plan b pill for you or give you a lift to the nearest clinic so you can get it yourself.

If you are planning on having regular sex with your boyfriend that I would say go to the doctor, and get on some birth control whether its the pill, patch, coil, implant or injection.

There are many types of contraceptives, so do some reading online to find one that you think would be best suitable for you. The only contraceptive, that would prevent against pregnancy and STD's is condoms so until you are on something then use then and continue using them even when you are on other birth control so it acts as a backup method and protecting you both against STD's.

Make sure your boyfriend also takes some responsibility for using birth control as it's not entirely up to you to use and get hold of it.

Each time you have unprotected sex, you both risk the chance of getting pregnant. Neither of you can know whether pre cum was released or not as you can't know. A woman can get pregnant at any time during her cycle but the chance is higher during ovulation therefore using contraception is important throughout the month and as prescribed by your GP.