Our 18-month old baby girl struggles to interact with anyone but her parents

I believe our little one is having a bit of stranger anxiety when we have people over at the house. If any of our friends come over, even though she has seen them several times, she would immediately start crying and cling to either mom or dad for reassurance. She will always ask to be taken to a room different from where the visitor is and that will calm her down. Our main concern is that my wife just started a new job recently and she needs to spend at least half a day in the office. I have a fulltime job but I can work from home. I am minding the baby at the moment but it can't go on for much longer as it is affecting my performance. Even though I can work remotely, my job is mentally taxing so it requires full concentration. That on top of the meetings that I have during office hours.​During the first week, we tried a childminder that would come over to the house and play with her for 3-4 hours while mom is at work. The idea was that she would entertain her while I did some work from home. In paper, it looked fine but it didn't work out. In one opportunity I had a 1-hour meeting and had to leave her with the childminder while I was in a room upstairs; a childminder that she had seen on several occasions. She cried her head off for the entire hour. Only paused for roughly 5 minutes I guess from exhaustion. We didn't try that again and I am minding the baby alone by myself while trying to squeeze in some work. Even if I am in the same room with the childminder, she wants to move rooms and gets very fussy making it even worse than me being with her alone.​In the past few weeks, we have also tried inviting 2 of our closest friends over so they can interact with her, basically trying to expose her to different people than mom and dad. While she would interact with them, it doesn't last more than a minute and would get really scared if she doesn't immediately see mom and dad around. We literally don't know what to do, so we both can get work done while knowing she's fine.​It is important to notice that we don't have any relatives where we live. We moved countries way before our little one was born so it's just the 3 of us. I guess that also didn't help her to get used to different people while growing up.​I've read this is a fairly normal stage during this age. I guess my main questions are, from your experience how long does this phase last? what should we do, just force her to interact and be alone with the baby sitter or one of our friends? would daycare help at all? Any tips are greatly appreciated! via /r/Parenting http://bit.ly/2M7SCny