I am 24 female (virgin )
I got intimate once with my previous boyfriend (he was my first boyfriend), during that session

1- I gave him a handjob, he was not wearing a condom. And after that, I touched my genital area without washing my hands

So It can be considered as indirect genital contact. Let's assume he has HPV, can I get HPV from what happened 

2- We did some dry humping and rubbing, there was no penetrative sex. I was wearing a thin layer of clothes but he was not.

Is there any chance of getting HPV or any kind of STD from this?

3- Please advise if there is any test I can do to make sure that I don't have any STD, especially HPV. I have been worried about it for 2 months now, I can not stop thinking about the possibility that I may be infected and I may infect my next partner.

STIs are harder to transmit than most people know.  Relevant to your situation, no STIs are ever transmitted through frottage (dry humping") or through clothing, even when the material gets wet with genital secretions.  In addition, STIs, including HPV are NOT transmitted through the transfer of infection on one person's hands to another.  For that reason, touching another person's genitals with your hands, or having a partner's hands touch your genitals after touching their own are NO risk activities.  

Nothing you describe suggests any need for STI testing of any sort.  As far as HPV is concerned, I do recommend that you get the HPV vaccine which is highly effective for prevention of HPV and its complications.

I hope that this information is helpful.  EWH

2- I started to notice abnormal symptoms like lower abdominal pain, vaginal itches, and yellow/brown discharge.

can this mean it's an STD/STI?

1.  The duration of time in bed is irrelevant.  What you describe was a no risk encounter 

2.  See above.  Nothing you have described suggests an STI.  I would suggest you see your gynecologist 

EWH

I have noticed a tiny skin growth on the area between the vaginia opening and the anus
I have asked you here about the risk of getting HPV from this single encounter and you suggested no need for testing

But to be 100% sure I decided to see a dermatologiest
The dermatologist couldn't decide if it was a wart or not. She said it could be a wart but in a very early stage so it's hard to tell.
She did an HPV test for me. But the test came out to be invalid. She said:
" PCR test couldn't determine if it is an HPV wart or not. 

Your skin condition is in such an early stage, that it doesn't contain enough cells to make the exact procedure."

Now she wants me to remove this skin growth and send it to the lap to see if it was an hpv wart or not.

I don't really know what to do now. This sexual encounter that I described before was the only encounter in my life and it was ~4 months ago 
And the size of this skin growth is very tiny and it doesn't grow
With this info, what is the severity of my case?

I am panicking here and don't know if I should do the removal, or just ignore it.

Please advise!

As a side note, I think you are over reacting here.  Given your concerns however, I hope you have gotten the HPV vaccine.  It is highly protective and if you are unvaccinated there is an 80% chance you will get HPV at some time in the future, monotonous or not.

We provide up to three responses to each client’s questions.  This is my 3rd response.  Therefore the thread will be closed.  Take care.  EWH