Girl is interested but no sex yet; Horniness is clouding my decision-making abilities

I'm seeing this girl and things are starting to get into relationship territory. However, I'm having difficulties with sexual escalation and am getting worried that she's getting bored. With other girls, I have little problem escalating sexually. Here's a rundown.

Some background on her

She's a Colombian Aupair who's been here for 6 months and lives with a family (so the logistics are bad). There's a language barrier, but she can understand me reasonably well. However, my flirting and jokes are often not understood. She's also Catholic and goes to church with that family every Sunday (she knows that I'm atheist and doesn't seem to mind).

1st date

We got coffee and went for a walk around the area. When we were about to play ping pong in my apartment lobby, I had to get a ball from my room and said something like, "do you want to come up?" She declined. This may be anti-slut defense and/or her being more traditional. No problem. Nothing physical happened, but I kissed her on the cheek at the end.

2nd date

We had sushi near her place and walked by the lake. I sexualized a bit here and there with some jokes and had her take a selfie of us where I kissed her on the cheek. So when we were alone at night, I said something like "we should kiss" to which she responded something like, "I'm getting shy", which really confused me (in retrospect, I shouldn't have said that). Anyways, a few minutes later, I just started kissing her. She stopped it after a bit. It seemed like she was worried it would escalate further. Subsequently, she asked me what I wanted. I responded something like "I'm not set on anything, but I like you" to which she said that she wants to get to know me and that she stopped talking to other guys on Bumble (she also said, that I was her first-ever Bumble date, which may or may not be true...).

3rd date

We had a picnic near her place (once again, bad logistics, but her area is nicer for picnics). We walked around by the lake again and made out a bit. She voluntarily showed me her Bumble, which confirmed that she had stopped texting other guys on there. It was a good 4-hour date. She started looking tired and yawning at the end, which is not a great sign, but she does wake up very early so it's understandable. I tried to schedule the 4th date at the end of the 3rd, but she said she's going out of town for a week. Nothing is set in stone; it was like a soft close. After she texted, "Me gusta las citas contigo!!!" and "Lindo diapara un londo chico!!", which translates, respectively, to "I like the dates with you!!!" and "A nice day with a nice boy!!".

Possible red flag: She's 24 years old and said she's had 8 boyfriends, none of which have lasted more than 2 months

My thoughts

• I have a strong feeling that she's acting more shy than she actually is, but I don't know how to break that barrier. I should have sexualized more on the 3rd date both verbally and physically. I should've had more intense make-outs, with some ass grabbing and hair pulling, but we were in public (even when there weren't people around, it was still not ideal). The texts after the 3rd date were nice but maybe too platonic.
• We've texted a fair bit and things look good, but I'm getting a gut feeling that she might be getting bored
• This situation is making me hornier and, as a result, more needy than usual.
• I'm tempted to ask her over text what she's looking for physically and/or spontaneously invite her over before she goes out of town, but I think both of these are bad ideas.
• I do like this girl and am not that interested in going on dates with other girls, but I feel like I should to get my mind off of it

Any thoughts or suggestions are much appreciated.