I might be pregnant with my 20 year old boyfriend, I am still with him but my mum has stopped me from meeting up with him as I'm only 16, hw can I tell my mum I'm pregnant if I am. She will kill me, I have skwl till nwt June, Please help

Don't say anything until you know for sure that you are pregnant. And if you find out for sure that you are here's a suggestion.
Write your mom a note and leave it for her and leave the house. Come back in a few hours after she has a while to calm down.

First find out for sure, do a pregnancy test and know for sure.
If you were having unprotected sex yes you well could be pregnant.
If you are not "meeting" up with him how are you still with him ?

And your mom is right in stopign you from seeing him, a 20 year old man has no business dating and having sex with a 16 teen.
In some part of the world, and in some states in the US, this is even illegal and he could end up in jail. Perhaps not in yours.

But what you do, is find out, if you are, it is not going away, so the sooner you tell her the better. Since getting proper medical care is important