Okay last month I got my period 2 days early , my mom tells me the date from your last period : your next period starts 4 days earlier and its always been like that for me , you know regular , last month in Feb. I was supposed to get it the 19 I got it the 17. This month in March I counted 4 days earlier to see if I get my period which was supposed to be the 13 I didn't get it so I waited the 15 since I got I got my period 2 days early and still nothing , so I was 3 days late and I have never been late on a period in my life I'm only 17. So the next day on the 16 I started to spot at first and it was a bright red color and I had cramping but not severe like I usually get them. This is the part where I get confused, I have been bleeding BUT its kind of like medium to light it wasn't heavy. I finished bleeding the 19 and it was a bright red and some brown then today on the 20th in the morning I had brown spots then it stopped so I took it as I stopped bleeding. I'm very much confused about this.I don't remember the exact date me and my fiancŽ had sex but he said he squirted once when we were having sex and I don't know how much sperm is actually needed to get a girl pregnant I know it takes one but eventually if they can't get to the egg in time they will die, please help me?

There is enough sperm just in the early fluids to get a girl pregnant, so any sex can get you pregnant.

With that said, it is common to have periods that are not always on exact time frame, you can even miss one now and then and not be pregnant.

But yes this is a sign of being pregnant, ( but also other things) So have you taken a home pregnancy test yet ?

Yes I took one but it came out negative I think I left it in the cup I peed in for too long

It may just be an off cycle. Many women will follow a regular pattern, usually a certain number of days from the start of one period until the day before the next one starts. The first day a period starts is always day one. It can be perfectly normal to be off a couple of days here or there. Your flow may even be slightly different once in awhile. Sometimes heavy with clots, other times not as heavy, few or no clotting, mild or strong cramps, etc. It is not uncommon for periods to be off a bit during the teen years as well. Not that they will be for everyone, just that it is not unusual if it does occur.

Either try another test in the next few days, or wait until next month and see what happens with your period at that time. Be sure to follow the directions carefully to get an accurate result.

One sperm will penetrate, but it takes many more to get it to that point. Odds are there would be enough in that one squirt. The chances of your being pregnant would depend greatly on whether you happened to be close to ovulation when sex occurred.

Try another test, see what happens. Good luck!