Need help with possible conception date. TW: SA

I’m not sure where this post belongs, but while trying to find an answer through google I saw a similar post here and was hoping maybe someone could help me

I recently found out that I’m pregnant and haven’t been able to get in to have a scan done yet, as there weren’t any available appointments until late in April

If anyone can help me with the math and trying to determine the likeliness of whether the father would be my boyfriend or the man who SA’d me, I would be very grateful

The key dates would be

LMP: 27 Feb 2026

Sex with my boyfriend: 8-15 March 2026

Date of assault: 18 March 2026

Negative pregnancy test: 27 March 2026

Positive Pregnancy test: 29 March 2026

I’m not sure based on these dates whether or not it is possible or likely that the person who assaulted me could be the father. I am trying to find somewhere that can get me in sooner for a dating ultrasound, but have seen conflicting results on whether or not it would be able to tell me with reasonable accuracy on when I conceived

I am an incredible mess trying to figure this out because my boyfriend and I have wanted this for so long and I am devastated

Does anybody know whether a dating ultrasound in the next week or so might be able to tell me if I conceived closer to the 8th than the 18th at this stage?

Thank you in advance for any help or advice that can be given here. Absolutely in shambles right now