Is she interested in me?

I met a girl through a good friend of mine that works with him about 2 months ago. Long story short i ended up getting her number and we talk to each other everyday if not every other. We already told each other that we were interested in one another but the only problem is shes impossible to take out jjust like me and her. We've hung out twice once at a party and another at applebees as a group. Ive askes her plenty of times most of the time she cant and the other she cancels last minute with a lame excuses. For example the night of the party we were suppose to get dinner then head to the party, we never went to dinner cus apparently she tried calling me the whole night and it never got through then i called my phone from hers at the party and it magically worked lol. The other 2 times she cancelled she wasent feeling well. I already asked if im wasting my time trying to take her out she said im not but shes just busy. And i also told her im getting tired of asking and how her always canceling on me is getting annoying and isnt fair. My friend also tells me that she tells him at work all the time that im the nicest guy shes ever met. My heart wants me to keep trying but i feel like shes trying to say shes rly not interested in me by canceling and doesnt want me to get hurt by actually telling me. She said she is interested and says shes sorry all the time and how much she sucks for never having time. Tommorow is my birthday and im going to ask her to come out with this weekend and if she cancels i was thinking about asking her like what the deal is between us or if she actually feels something. If anyone has any advice please feel free to let me know. I appreciate the time thanks you